in games I GM, each Barrack Component in a ship with Invasion bridge gets one of these for free. (considering a Barracks in a Cruiser should hold up to 100k troops, we needed a better transport to land)

Wiki on it:

http://wh40k.lexicanum.com/wiki/Devourer_Dropship#.UoEOnKxmDts

Ship on the background looks a bit larger, but GW just isn't that good in scaling things sometimes (also, that's a painting, so you could consider some exaggeration from the artist's hands on picturing the scene even more epic):

http://wh40k.lexicanum.com/wiki/File:Img008.jpg#.UoEOzaxmDts

Name
Devourer Dropship

Tactical Speed
10m/5 AUs

Cruise Speed
700kph/2VUs

Man.
-20

Structure
80

Armor
- Front 40
- Side 35
- Rear 30

Crew
Pilot, Co-Pilot, 6 Tech-Priests, 1 Enginseer, 2 Gunners

Carrying Capacity
5000 humans + 50 Leman Rus Tanks/Chimeras (or 10000 humans total)

Availability
Extremely rare

Special Rules
Spacecraft, Reinforced Hull

Weapons:

2 twin-linked lascannon dorsal turrets.

I think you should increase carrying capacity, especially carring humans. Leman Russ is described as weighting 60 tonnes. 50 x 60 = 3000 tonnes - it should be quite more than 500 humans.

My advice - when in question multiply by 10: 5000 humans + 50 tanks (or 10000 humans total or 100 tanks total).

I agree Wincent, already made the change.