The Peavey 60/60 is 60 watts RMS per channel (stereo) into 16/8 or 4 ohm speakers or 65 watts mono and it's a bit heavy (30lbs)! The smaller alternative is the 50/50 (1 rack) which is 50 watts RMS per channel (stereo) into 16/8 or 4 ohm speakers or 55 watts mono, but it is not much lighter at 26.8lbs. I don't think you can win on weight with tube amps because of the power transformers (No pain no gain!
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From a sound perspective I think the Peavey adds less of its own character to the sound (which people complain about!). My personal opinion is that it is probably more 'transparent' then most valve amps but till adds the tube 'warmth' to the tone:).
From a cost perspective you are right about 250-300 USD. I paid just over $200 and then spent about another $80 to re-tube it with some 'premium' tubes which improved the sound significantly (came with stock tubes). The 50/50 is more in demand so can be a bit harder to get hold of other than that the other differance between the two is that the 60/60 uses 6L6 tubes in the power stage and the 50/50 uses EL84's. Only negative with it that I can think of is the cooling fan is a bit loud and when I first got it I figured I would repace it with a quiter one. But honestly once you start playing it's not that noticable (or maybe that has something to do with the volume I play at! ;))
More info here:
http://www.peavey.com/media/pdf/manuals/80301119.pdfand
http://www.peavey.com/assets/literature/manuals/80301636.pdf