I dont have any experience with them personally, but I have heard more good things about them than bad...

Some of the bad uns:

1 the price

2 the retainer bands can slip off at the worst times (as with most expandables) ie, in the stand...

3 the ferrules are not very stout. lots of broken and bent up ferrules. (so Ive heard)

Like I said, thats only a few of the bad sides of them, but they seem to attract way more positive views than negative... You prolly wont go wrong by ordering a pack.