I will disagree with most here.
If Efren of 20 or 25 years ago is indeed better than Shane of year 2012, that would mean that there was no progress in quality of pool game. None what so ever.
And that would also mean that future top guys from year 2032. for example might not get any better than current top guys like Darren, Shane, or top guys from 25 years ago. Have we reached the human limit? Already? How believable is that?
I don't know what is it with pool fans, but most think that peak performance of Efren is some kind of pool perfection and that nothing can top that, ever...am I close? My opinion is, no matter how good one gets, there's always room for improvement.
There is a constant progress in every single sport, physical types, non physical types, other cue games...you name it. Is pool some kind of exception? I don't think so.
I like both players very much, but I'm no fanboy of either. Shane is better, no question.
I think the virtual top performance level in the game was reached over 60 years ago. I see your point that there's always room for improvement, but until SVB and others are running over 100 balls EVERY day or stringing 9 packs together at least once per tournament, then we're still stuck at roughly where the game's been for decades. I find it interesting that Mosconi's run record still stands after 4 decades...there are plenty of straight pool players out there trying, some have come close, but not yet. I don't see dramatic improvements in performance coming soon and don't see a lot of dayight between the top gear of players in the 80s and today. SVB is potentially the best ever, but let's see him get there first!