I dunno. Delta Ser and Beta Aquilae were pretty much the only Terran colonies not heavily ravaged, and even they had a sizable number of Shivans and/or HOL in them at various points in time. (I am of course excluding Luyten, since my account of events there are likely to be different from other campaign writers'.)
I'd put more money on even an emasculated GTA than I would with any of the Blocs save perhaps the Antarans.
I mean, the Luytenese had crap systems (3 red dwarfs -- four, technically, since Luyten's a binary), the Adharans were in the middle of nowhere and had no infrastructure at all, and the Regulans were a syndicate (infer corruption and an economic focus rather than military).
But yeah, I agree with you Ace, Sol would probably have done far better than the various Terran colonies would have on their own prior to the GTVA's formation.
The reason I say this is, it's really the Vasudans who have been the economic driving force of the GTVA IMO. Even with the destruction of Vas Prime, those who evacuated (presumably those who could afford to get out fast) brought their cash with them. The result was a lot of Vasudan money to invest, a lot of which ended up in the Capellan and Adharan sectors which had to build everything from scratch.
And of course investment in the traditional Vasudan sector wasn't as safe a bet with the HOL rampaging around -- besides, there was lots of cheap Terran labor and open land.
Whereas, by contrast, the vast majority of Terran cash was in banks in Sol, especially after the decimation of most of the outer colonies, thus likely impoverishing large numbers of Terrans and creating an endemic crime problem.
Okay, I'm done. Proceed to massage your temples for relief.