Originally posted by K David (Right now, though, I'm debating between the Pentax 55-300 and the Tamron 70-200 f2.8)
Sorry for digression but this caught my eye; these two lenses aren't really comparable as they serve different purpose. I don't have 55-300 but I had 50-200 and I have the Tamron.
50-200 is a compact, decent telezoom that you take with you for a stroll if you feel like you might shoot long.
Tamron is a kilo+ of high quality glass you take when you *need* the IQ and/or 2.8, otherwise it stays home.
I don't really shoot much above 50mm (and that mostly at dance shows of my children in places with poor lighting). If I was into it, I'd consider having 55-300 too; Tamron is just too heavy for casual stuff.
Having said all that, I *did* carry Tamron around a lot this year.