If you compare them vs. their competition, they are both the best by a good margin. It's difficult to measure that, but neither one has an equal in their day and age. The only question is whether Paul can stave off the younger generation as they are coming onto the scene like Ken did until he was 35 or so.
If you compare them with world titles, then I'm not quite sure how to adjust. If Paul gets to 12, that'd be a greater feat than Climo's 12 due to the competition. I'd say if Paul gets to 8 or 9 then that'd be equivalent to Climo's 12, but that's just my opinion.
As for Paul not being able to play with slower discs, I disagree, and I have quite a few ideas to back that up. I've seen Paul throw a putter 440. He throws Buzzzs, Zones, and Lunas more than anything else. He can throw BH rollers with slower discs just as well as Climo could. He's even been a proponent of decreasing the rim width limit (to 1.8cm, which is speed 9). All of this on top of the fact that he's also honed in a world-class forehand. So to anyone who wants to ask the questions of, "Could Paul be as good with the limited disc selection/technology back then?" and leave the answer hanging as if he couldn't, I'd reconsider.
Could Climo learn to throw a FH with the newer discs that allow for it? Sadly we can't say for sure, but the educated guess would say that he could. Dude could throw any line that people commonly threw back in the day. Heck, even if he couldn't learn a serviceable FH, his floor would be James Conrad (please don't start a Climo vs. Conrad thread).
Someone was talking about Paul not executing the shots 100% of the time like Stokely said Climo could. You're right, he couldn't. However, Stokely commonly exaggerates (that's how he talks, I don't think it's a bad thing), and I guarantee you Climo wasn't even close to 100%. Maybe that day where he rattled off 23 straight birdies he was.
Here's where I'm going: they are both amazing to watch because they both have a drive to work hard enough to be the best, and the killer instinct to make it happen on the course. They both made sure they were the best prepared player heading into the weekend, and then each of them had a different mental edge, but they both had the mental edge on their opponents. From what I've seen, Climo just acted like he was the best, sort of like Tiger does, where everyone knows he's the best and he uses that to his advantage. Wish I could have seen it. McBeth is stoic, making the right decisions and then executing on those decisions. If he needs to take a risk to win, he will; Idlewild is a perfect example of him taking huge risks on the last few holes and it not working out; Maple Hill last year (hole 17 putt) is an example of a risk that did work out.
Arguing "who is better" is fun, but let's make sure to sit back and enjoy the ride. I love watching McBeth play ten tourneys a year because I know that, if he's in the mix then it'll be a good finish. I wish I could have watched Climo play more, and it's great when people upload vids of the old days. If only we could see King Kong vs. T-rex instead of debating it.