Ex, thanks for posting these.
I go back and forth on my feelings about Three Fly. The first time I saw a performance of it, I was stunned. But I also think that a Three Fly sequence isn't a satisfactory magical routine on its own. (I know this opinion isn't original to me - I think Chris Kenner has even said something to similar effect, though I could be wrong.)
I own several different handlings of Three Fly, but only one of them uses any kind of gaff (a pretty standard one) so I can't really comment on the practicality of any of the expensive versions. After watching the videos though, I think that, like most effects, the quality comes down to the performer.
My favorites of the videos are Daryl's, Chris Kenner's, and Ponta's - a pretty wide range of routines as far as methods go. They were my favorites because they were mystifying, technically proficient, fun to watch and well-paced.
I also think all of them have flaws, and have yet to come across what I think is a "perfect" Three Fly. For this reason I don't perform Three Fly for anyone, although I am interested in Eric Jones's Mirage Et Trois, R. Paul Wilson's TheFLY, and, now, the Wonder Coin set.
(As a side note, the thing I perform currently that's closest to a Three Fly routine is my own handling of Geoff Latta's The Trick With Three Coins, found on volume one of the New York Coin Seminar DVDs. It's not technically a Three Fly, but I like how it combines the mystery of a closed hands coins across with the visual appeal of coins appearing at the fingertips. It also has an opening production sequence, a closing vanish sequence, and in my handling, ends clean and instantly reset.)
Anyway, to answer Exodus's original question, whether or not expensive gaffs are worth the price, I think it completely depends on the skills and presentation of the performer. The impromptu versions are not identical to the gaffed versions, but presentation can make them equally entertaining (or, as in the case of the Come Fly With Me Demo, it can trash even a technically sophisticated routine) and that's all that interests me in the end.