lifeis11 wrote:pardon my ignorance, but i would want NO ridge for my GS3, correct?
As Alex said above, it's a personal preference, and the GS/3 itself (or its portafilter) won't care.
You would use the same tamper (58.4mm recommended) either way. If you don't have the ridge, there's no little groove on the inside wall where loose grinds can hide, and it's easier to get the basket out of the PF if you like using multiple baskets. So on balance, I like the ridgeless version, especially since I dose and tamp multiple baskets outside the (un-sprung) portafilter and then run off the shots back-to-back in series.
That said, I have several ridged VSTs purchased before the ridgeless version became available, and I can assure you that I feel no pain when using them.