In reply to UKC Gear: sorry to bump an old thread, but couldn't post earlier - I really like Holdz, they are very finger friendly & you have to work them to find the best grip. They are not overly featured, so they're good for setters trying to force sequences. They also clean up well compared to some other makes of 'normal' holds.
Polyurethane holds (so ill, slap etc.) are good & seem to be the way forward among hold manufacturers, but may have more advantage on roped routes where weight is at a premium for the setter. I agree that I would rather break an occasional hold than snap a t-nut (of which i have snapped quite a few now with the polyurethane ones), as it is just way more work exactly when you are usually rushing to finish setting.
Also, a couple of minor things - the polyurethane holds are much warmer to the touch than 'normal' holds, meaning they sweat up a bit easier & have a less pleasing feel to the grip & they also have a bit of flex to them which again just feels slightly odd & definitely disturbing on the smaller crimps.
My 2 cents thrown in anyway.
Cheers
F