There is no apples to apples comparison. According to BFG, RT is plain wrong, especially where ship speed and weapon ranges are concerned. FFG provided more variability, or possibilities in the details. The same applies to armor. There is more variability in RT. Interpretation is required, not suggested.

Yep! The TT's focus on speedy turn resolution and lower dice ranges means it's just going to be way more abstracted.

The only thing I could recommend is to use the TT as a rough guideline for how much better or worse one thing is in relation to another, or whether they are on roughly the same level.

I'll try and write what I was considering.

BFG -> RT

Endeavor & Defiant:

Speed 20cm -> 6

Shields 1 -> 1

Hull 6 -> 60

Armour 5+ -> 20

Turrets 2 -> 2

Maneuver 90 -> 12

Cost Endeavor: 120 -> 57

Cost Defiant: 130 -> 58

Falchion:

Speed 25cm -> 8

Shields 1 -> 1

Hull 1 -> 36

Armour 5+ -> 18

Turrets 1 -> 1

Manuever 90 -> 17

Cost 35 -> 42

Mars/Overlord/Armageddon:

Speed 20cm -> 5

Shields 2 -> 2

Hull 8 -> 70

Armor 5+ -> 20

Armor 6+ -> 24

Turret 2 -> 2

Maneuver 45 -> 10

Cost Mars: 270 -> 71

Cost Overlord: 235 -> 64

Cost Armageddon: 245 -> 63

Lunar/Tyrant/Dictator

Speed 20cm -> 5

Hull 8 -> 70

Armor 5+ -> 20

Armor 6+ -> 24

Shields 2 -> 2

Turret 2 -> 2

Maneuver 45 -> 10

Cost Lunar: 180 -> 60

Cost Tyrant: 185 -> 61

Cost Dictator: 220 -> 63

Dauntless

Speed 25 -> 7

Hull 6 -> 60

Shields 1 -> 1

Turrets 1 -> 1

Armor 5+ -> 19

Maneuverability 90 -> 15

Cost: 110 -> 55

Sword

Speed 25 -> 8

Hull 1 -> 35

Shields 1 -> 1

Turrets 2 -> 2

Armor 5+ -> 18

Maneuverability 90 -> 20

Cost: 35 -> 40

Firestorm

Speed 25 -> 8

Hull 1 -> 38

Shields 1 -> 1

Turrets 2 -> 1

Armor 5+ -> 18

Maneuverability 90 -> 20

Cost 40 -> 41

Cobra

Speed 30 -> 10

Hull 1 -> 30

Shields 1 -> 1

Turrets 1 -> 1

Armor 4+ -> 15

Maneuverability 90 -> 30

Cost: 30 -> 30

Viper

Speed 30 -> 11

Hull 1 ->25

Shields 1 -> 1

Turrets 1 -> 1

Armor 4+ -> 14

Cost 45 -> 27

Vagabond

Speed 15 -> 4

Hull 1 -> 40

Shields 1 -> 1

Turrets 1 -> 1

Armor 5+ -> 13

Maneuverability 45 -> -5

Iconoclast

Speed 30 - > 10

Hull 1 -> 28

Shields 1 -> 1

Turrets 1 -> 1

Armor 4+ -> 14

Maneuverability 90 -> 25

Cost 30 -> 29

Repulsive

Speed 20 -> 5

Hull 10 -> 85

Shields 2 -> 3 (with option for 2?)

Turrets 3 -> 3

Armor 5+ -> 19

Maneuverability 45 -> 8

Cost: 230 -> 69

Avenger

Speed 20 -> 5

Hull 10 -> 90

Shields 3 -> 3

Turrets 3 -> 3

Armor 5+ -> 21

Maneuverability 45 -> 5

Cost 220 -> 70

Exorcist

Speed 20 -> 4

Hull 10 -> 85

Shields 3 -> 3

Armor 5+ ->20

Maneuverability 45 ->4

Cost 230 -> 71

A few things come to mind. First, the Firestorm is the only place where turrets don't match up exactly, that's probably a typo. Second, The Vagabond is an odd one out. Third, maneuverability is mostly based on class of ship in RT than anything else. Fourth, I need to take a much longer look at the costs (maybe add in the SP for outfitting them the default way to figure that out?) to figure out Cost ranges... However, you can figure out a few useful things fairly easily:

Grand Cruisers have the most variance of their statistics

Speed 15 means a speed of 4

Speed 20 means in a Cruiser means a speed of 5

Speed 20 in a Light Cruiser means a speed of 6

Speed 25 in a Light Cruiser means a speed of 7

Speed 25 in a Frigate means a speed of 8

Speed 30 means a speed of 10-11

Hull 1 in a Raider means 28-31

Hull 1 in a Frigate means 35-38

Hull 6 in a Light Cruiser means 60

Hull 8 in a Cruiser or Battlecruiser means 70

Hull 10 in a Grand Cruiser means 85

Maneuverabiltiy 90 in a Raider means 25-30

Maneuverability 90 in a Frigate means 17-18

Maneuverability 90 in a Light Cruiser means 12-15

Maneuverability 45 in a Cruiser or Battlecruiser means 10

Maneverability 45 in a Grand Cruiser means 4-8

Turrets map 1 to 1 in all ships

Shields mostly match 1 to 1 in all ships

Armor 4+ means 14-15

Armor 5+ in a Frigate means 18-19

Armor 5+ in a Light Cruiser, Cruiser, Battlecruiser, or Grand Cruiser means 19-21, with Grand Cruisers having the most variance and mostly being the only class that can treat 5+ as 21.

Armor 6+ means 24

So, yes, there IS an apples to apples comparison! It's right there, in the data!

So, given that, Strike Cruiser (as Light Cruiser, which it is the size of) should have...

Speed: 7

Hull: 60

Maneuverability: 12-15

Shields 1 - 2

Turrets: 2

Armor: 24

Gladius should have:

Speed: 10

Hull: 35-38

Maneuverability: 17-18

Shields 1

Armor: 18-19

Turrets: 2

And the only thing wrong with my strike cruiser is my armor is too low, and my maneuverability is too high, and it is possibly a tad too fast in normal space (unless if speed 25 just means a speed of 7-8 in general, which is plausible). Also I found some old writeups for the Arbites ship, which seemed to be more badass than the Astartes one (!). Unfortunately, there aren't stats for Heavy Frigates in BFG... Editing my stats appropriately, then.

SM strike cruiser speed could just mean that all SM strike cruisers have a Tech Marine aboard, and can reliably perform the Flank Speed Extended Action every turn.

Possibly! Also, I added the Hawking, being another 'super expensive with super capabilities' Light Cruiser.

Different weapons ranges and damage could also be important, but the RT RPG seems to lack the equivalent batteries so these might have to be houseruled. A Space Marine Strike Cruiser has port and starboard weapons batteries with range equivalent to Imperial cruisers and frigates (shorter than battlecruisers), but lower damage output (3 vs 4+).

I completely ignored the weapons bit for conversions and finding hull equivalencies.

EDIT: I took the beta document down because I'm working on the final version now.

It should be finished in a few days and will be uploaded to my dropbox and linked in a new thread on this forum.

Yea, now I did as much as I could to unambiguously follow the numbers from BFG. Did you use my math chart thingy?