I love ST2 - it's the first editor I've really sat down and learnt properly, and I've got a tonne of value out of it. The features ST3 are bringing to the table - at this point - don't seem worth the upgrade. I dislike the idea of paid upgrades for just about any software, even though I understand the economics.

Ultimately, I think continued development of plugins will force the issue, and upgrades will be required.