Over in the comments on the post about the scarcity of non-D&D games in the Old School Renaissance, JDJarvis raised the issue of whether GURPS is the new and improved Fantasy Trip system. I still have my copies of The Fantasy Trip books, and I played a lot of GURPS, too, so it may be surprising that I disagree completely: GURPS is not The Fantasy Trip. It is clearly related, but they aren't as close as people think.
The most obvious thing to say first is that GURPS cannot legally be a new and improved Fantasy Trip. Steve Jackson designed The Fantasy Trip for Metagaming Concepts as a work-for-hire. It began as a man-to-man medieval wargame, Melee, which drew from traditions of board games instead of from miniatures wargaming. Wizard was added as a fantasy spell dueling companion, and then Howard Thompson saw the possibility of creating a cheap competitor to D&D, so he asked Jackson to expand it into an RPG. When Metagaming went under and Jackson moved on, he was unable to get the rights to TFT, so he designed a new man-to-man medieval wargame called simply Man-to-Man. GURPS is descended from Man-to-Man, not The Fantasy Trip.
Man-to-Man and Melee share some similarities, but many of them are just typical of board wargames: hexes instead of squares, each hex the size of one figure, a tight focus on one action per turn, combined with very short turns and success rolls required for most actions. Because figures in strategic or tactical board games typically have only a few stats, TFT is restricted to four, and GURPS is restricted to six, some of which have the same names. Jackson also deliberately chose a d6-only approach for both games.
Many of these elements are shared with other RPGs; the five-to-six second turn and success roll for every action, combined with distances measured in hexes or squares approximately the size of one figure, has pretty much become the standard. So is using one of the main stats as a target number for roll-under success rolls, which arguably could be said to be a true survival of TFT in GURPS; but then, BRP had some roll-under attribute checks, as did Champions/Hero System.
GURPS is, in some ways, more a descendant of Champions than The Fantasy Trip. Both TFT and Champions roll 3d6 less than a target number, but TFT adds one or more dice for more difficult actions, while GURPS and Champions would use adjustments to the target number. Even more obvious, the GURPS character building system is more like Champions than TFT, with a pool of character points spent to buy attributes, advantages and skills, and disadvantages to get extra character points. TFT instead only uses a small pool of points split between the three attributes, with no distinction in costs, followed by purchasing Talents with IQ points. Talents don't really work like either advantages or skills in GURPS; they all require a minimum IQ score, and instead of changing the target number for skills, they reduce the number of dice rolled. Jackson basically abandoned the TFT Talent system to design a more Champions-like system.
I said in my reply to JD that the way damage is marked off against an attribute -- ST in TFT, HT in GURPS -- and the damage/fatigue split, with fatigue being erased after shorter periods of rest than damage, could probably be considered a true inheritance from TFT. But again, Champions does this, and unlike TFT, Champions has separate stats for maximum fatigue and damage, as does GURPS.
Probably the closest resemblance GURPS has to TFT is in the spell system. TFT uses a minimum IQ score restriction, which GURPS only uses for a few spells, but GURPS Magic does have an elaborate spell prerequisite tree which makes it feel a little bit like TFT. It's also a roll for success spell point system, exactly like TFT. A few spell descriptions, as well as the alchemy rules, resemble TFT descriptions.
So, on the whole, although there are clear borrowings from TFT, I would not today consider GURPS to be an improved Fantasy Trip. Aside from the elements that clearly resemble other games more than they resemble TFT, I think in my personal opinion it's not really an improvement.