I've long appreciated the BF/SF twin, especially the early silverfaces. But they're too heavy, too loud. The Pro Reverb is an obvious alternative at 40 watts (not the later, MV SF models which were 70). But still rather heavy.
The lo power tweed twin is a different thing, and I can recommend it highly. Mine is the '57 RI from Fender, and is one RI amp totally worthy of it's original name. Probably just under 50 pounds. Not the scooped, cavernous clean of the later ones. Way more mids, plus alnico speakers, even two rectifier tubes. 40 watts, and it's a loud 40 watts. As rich sounding and responsive feeling amp as I've come across. My Guild S-90 loves this amp!
MD