The IPT certainly did provide some good insight into the game of 8-ball, especially for younger players who may have never seen 8-ball played at the professional level. I remember when I was young that I would occasionally see 8-ball on tv, with guys like Mizerak and Hopkins battling it out, there was a long period where I never saw any professional-level 8-ball, however.
It seems to me that at the professional level the difference in the luck factor between 8-ball and 9-ball is pretty small. I would concur with earlier posters as to the main areas of luck in each game, but I would also submit that another prevalent factor in 9-ball is that a player is much more likely to end up with an unintentional safety after missing a shot. This seems to occur just as often as someone snapping the 9 or fluking in a ball. As a matter of fact, my opponents always seem to have an uncanny ability to hook me after every miss, and the more weight I'm giving up, the better they get at it, lol.
I like 9-ball for it's elegant simplicity. I also like the fact that, since there is always only one ball the shooter can legally hit, there is potential to play defense on almost every shot, unlike 8-ball where, especially early in the game, your opponent has so many targets on the table that it may be impossible to hide him from all of them. I also like 8-ball, though, mostly because it is played with a full rack, and thus requires the shooter to play close position, to play position at times by "floating" the cueball into an area instead of using 2 or 3 rails to get there as we commonly do in 9-ball, and to learn how to deal with clusters and other troublesome situations that do not come up quite as often in 9-ball.
They're both good games, but they both definitely have their shortcomings, IMO. I would say that a player who restricts himself to one of these two games is not going to develop certain skills as rapidly as he otherwise might. If you had to pick just one game to play, it seems to me that your best choices would be rotation, one-pocket, or 14.1.
Good rolls,
Aaron