No one levels string anymore Garith. I cant personally say I have ever missed one dispel in EXP up to level 74 so far. 500,000k or a little added range. I got better stuff to drop 500,000k on unless you can tell me where someone would actually need one of these.
I don't have any trouble dispelling using a string instrument, I don't use this either... Also 9 times out of 10 at 75, as a bard, you're not the one dispelling... So I don't see much point in spending 300k on an instrument that's got not a lot of use.