The generosity of the demo is something which made the game attractive to me in the first place.
Demo's which limit time or amount of plays make you feel like the developers are trying to force you into a quick sale.
LFS on the other hand, they've said "here's a track and a few cars, go for it! - and if you want more, you're welcome to buy"
If LFS had it's time over, I would probably vote the demo should be XFG+XRG only right from the beginning, even those cars alone combined with the track and unlimited use is damn generous in comparison to other demos.
However as it is now, its unfeasible to suddenly take the XRT out, its taking something away which was available before. People wouldn't move to the latest version, instead remaining on the last demo that featured the XRT
People do live full time in the demo, I myself played it for about a year I think, before I suddenly decided to buy a license. I had the money, sure, but somehow it was too difficult, until my parents let me use their credit card.
I guess that brings us back to another problem - if LFS cost 15pounds for S1 and 30pounds for S2 - available boxed in game stores meaning people can buy with cash, I am sure alot more demo users would go out and buy it. It's just the whole "online thing" of using the credit card or money orders, where people put up the stone wall (ie. "I haven't got enough money!!") or just throw it in the "too hard basket"...
.... and then go for another 3lap race at blackwood