I'm running a PBWF (Play By Web Forum) and a face-to-face + GRIP + PBWF, both set at about the same time (1115, started on in 1114) in the Spinward Marches.
One is a group of diplomats, scouts, SF types working for an Imperial Agency doing a variety of diplomatic and espionage operations.
The other is the crew of a free-trader, all formerly grew up on Focaline and most mustered out similarly after 5FW in about 1112-1114. They recoverd the ship from a kind of unknown grave (long story) on Inthe, but in doing so made some megacorp friends and some Ine Givar enemies.
Both versions I use a slightly modified MT ruleset (I apply stat damage during the firefight, not after). I have yet to decide if I'm going to use Vanilla Rebellion, Wounded Collosus (Thanks LEW) or my own home brew Rebellion. They'll have to wait and see!
I use DGP's World Builder's Handbook, Ship's For Windows (MT ship construction), Guns! Guns! Guns! and a number of other handy bits for world detailing and techhead stuff.
Most of my players in face to face are mostly military or ex military types, so our combats tend to focus on realistic tactics (a bit of action movie, but not too much) and they tend to be ugly for whomever has the worse plan or worse luck.
Why MT? Task system and Skill System and my favourite chargen (the extended stuff). I can run the entire game with little or no reference to any manual, and my players don't have to know aught but how to roll 2D6 and how the skill system works. All the rest I worry about - the focus becomes on the game, not on mechanics, not on feats or perks, or disads, or whatever oddball mechanics other sets have introduced. CT with a task system would BE MT to me.
TNE was okay, but I didn't like the ruleset except for Brilliant Lances. T4 was a bit of a waste of my money, as it was part CT, part MT, part... not so useful. T20 was okay, but since I hate feats and some of the rolling mechanics of D20 for Traveller, it'll just be a reference work. GURPS has lots of excellent reference material, but toooo maaaaany ruuuuleeeessss. (Yes, you can play with fewer, but the truth is I'm just not fond of the mechanics - I am fond of some of the setting/support materials like First In and Ground Forces). And T5 doesn't even make my radar as roll-under just makes me cringe and shiver.
Of course, other views disagree
But for my players, none of whom own anything other than some CT books and most of them not even that, and who want to play a game where they don't *have* to know much about the rules and can focus on characters and their reactions, MT is a near perfect vehicle.
And that's even with all the damn errata....
Oh, and did I mention the Virus bites?