I've used a few other tube bass heads recently and while they all sound sublime, there is a certain practicality that is lacking. My vintage Ampeg V-4B weighs a frigging ton. My Sunn 200S is better but still very bulky. It's great to use on rock gigs with the larger speaker cab but just plain awkward with 1x12 or 1x10 cabs like I'd use for smaller rooms and Jazz gigs. An old Traynor Bass Mate is getting down to a manageable size and weight but the wattage is too low.
This PF-50T is smaller and lighter than any of the above mentioned amps and the 50 watts is adequate for most gigs I do. That to me is the real beauty of this head - I now get to enjoy the organic response of an all-tube amp in lots of settings where it had previously not quite been practical.
It does take up at least one hand for loading (I use a tote bag for the QSC K8 powered speaker, may soon try a Gator GP66 bag). I can't sling it over one shoulder like I do with my trusty old Markbass LMII. But I don't enjoy using that amp anymore now that I'm used to having all-tube all the time. (Don't get me wrong. The LMII sounds fine - always has - but the feel just isn't the same.)
The PF-50T can be fussy. It does seem to like to be driven a certain amount - not too little, not too much. More than once I've found myself swapping out speaker cabs in between sets to get things more in the right zone. I find gain staging has a huge effect on the response - I usually prefer leaving the master volume all the way up, which makes it emulate the way my older amps work.
On account of its being brand new, I tend to trust the PF-50T more than I have my older amps. The user-adjustable biasing with handy guide lights means I might go years without having to take this thing to my tech! I haven't gotten to know the built-in DIs as much as I'd like - the one time I used the "pre" one, it did sound great. (Can't wait to try the post-transformer DI in a recording studio.)
I'd like to see other makers explore this concept so we have a few more choices in this size and wattage range. But for now, the PF-50T is the only game in town and for me it has been a real game-changer!
EDIT: I sold this head after a year of gigging. I had an issue with the signal cutting out, which my tech traced to the "Ultra HI" switch. When attempts at cleaning failed, he bypassed the switch electronically which was apparently relatively simple to do (or undo if desired). Replacing the switch would have been quite a bit more troublesome.
While the tone could be nice sometimes, I did find it to be somewhat gutless next to my similarly-rated Sunn 200s. The Sunn does have more than twice the weight but much of that comes in the form of two huge transformers, which dwarf those found on the PF-50T. The Ampeg seemed to lack the glorious distortion capabilities my other tube heads have when pushed - rather than fuzz, it just compresses and disappears in the mix. These concerns (along with the minor hassle of the tote bag) caused this amp to fall out of favor for me. I may try the Mesa "Prodigy" amp next, which seems to have a nice manageable size & weight but has a handy top handle and much more substantial wattage.