The CT CD is an excellent resource for MGT. Weapons need some tweaking. MGT adds damage for the result on the "to hit" roll, so you have to reduce the damage roll range for CT weapons. Just look at the stats for the weapons in both for a guideline. Ships might need changes depending on your campaign, most other stuff is usable as-is or with on-the-fly changes.
T4 uses roll-low-is-good compared to roll-high-is-good, and it uses variable numbers of dice for some things, but not in a way that's goiing to affect what you bring into MGT for most things (skill checks.) MGT appears to be introducing a "lite" version of the variable number of dice mechanic for "heroic" skills in Judge Dredd.
I love both the CT and MGT systems. I enjoy reading the CT stuff more, since I like rules to cut to the chase, and CT has a clean sparse writing style to the rules. But I'm presently running MGT, with lots of CT underpinnings.
The MGT main book has a lot in it, you don't need much more in the way of rules for an excellent campaign (heck, you've already got the GT stuff for non-numbers based material.) I'd recommend downloading the free MGT Mercenary and High Guard SRDs to get the new skills from those books, too, when starting out. You can also get free stuff from Signs and Portents downloads. For a few bucks, you can get some great careers to flesh out the main book from the Spica Publishing
careers book.
