I've seen 3 Rookie Xwings take down an ISD. (Early mission, Rebel Assault 1) They were meant for capitol ship engagements not for fighting fighters, significantly reducing their point costs relative to X-wing as a game. Big ships were always vulnerable to Torpedo Strikes from manueverable ships. Hell, the empire built smaller anti fighter ships to combat the problem. So yes, what I described is a Star Destroyer trying to deal with nuke loaded gnats.
The Empire built smaller anti fighter ships to combat the problem of '3 rookie X-Wings' taking out their ISDs?
Are you really saying that an ISD in XWMG should be the equivalent of 75pts worth of rookie X-Wings?
You are right, an ISD would NEVER be deployed without a compliment of fighters in it's hangar deck; because that is just plain stupid.
Those accompanying fighters would just compound the point difference that VandorDM mentioned. To illustrate the point lets pretend that it will cost 200pts for a stock ISD(HA! Really? *Face-palm*) miniumum. 100pts TIE fighter escort(As if an ISD would ever have only 8 Tie fighters. There are that many Lamda Shuttles aboard alone.)minimum. We are at 300pts already.
A CR-90 is gunna be 150(ish)pts. Do you really beleive that an ISD would not be worth drastically more than a CR-90? Without dratically reducinging it's capabillities to the point that it is no longer an ISD?
What you are asking for is something that looks like an ISD, but would actually play like a Vigil.
Therefore, be contnent with a Vigil and leave the ISD "off camera."