I already replied on your other thread about possible MPG increases w/ the VX tranny in a Civic DX...generally 6% - 10% increase. As far as losing startup speed, I personally love the tall gearing. You don't need to run through all the gears to get up to cruising speed (I often shift from 3rd to 5th), and you can drive at higher speeds in the lower VX/CX gears than you can in the DX gears.
My only complaint is in heavy stop and go traffic that's more than a few minutes. It's hard to creep in first gear w/ the VX/CX tranny due to how tall it is. But most of my driving is highway (and I avoid stop and go traffic), so it's not a problem for me.
That said, my former '95 VX had 225,000 miles w/ the original clutch when I sold it 3 months ago, and it still felt like brand new.
Personally I would get the newer Civic. But if you opt for a 92-95, you better check it over real good for rust, especially in the rear quarter panel area. They are notorious for rust back there for some reason! Bring a magnet so you can test if it has ever been repaired with bondo back there.