To those with the player control network, is it something you use regularly? Is it essential, in your opinion, or really not necessary?
necessary ? no ... useful? heck yes.
I use my 4ohm Walkabout 12 mostly by itself. But on 20-30% of my gigs I combine it with a 4ohm Scout 15 ext cab. I'd say that the user adjustable crossover and tweet control is
somewhat useful with the Walkabout 12 working as a standalone. I basically just set the control to 5k "full" and cut the tweet -1db. My Jazz basses are very happy with than setting. Plenty of old school thump, with plenty of presence to be heard in a band mix.
BUT, when adding the other Scout cab to the mix, you can do some mighty nice things with it. For example, when I stack mine, I set the Scout 15 to the "full" 5k crossover setting and roll the tweet off -1db, I set the Scout 12 to the 3k setting, and push the tweet +1db. So, really the 15 gets a full range of the amp output and has the tweet related highs cut a bit, and the 12 gets more of a low-mids/mids flavor plus a slight push in the highs from the tweet. IME, and to my ears, it's a very nice, and noticeably useful control set to have at your disposal.
I have also used my Scout 12 and Scout 15 cabs with other amps. 78 Fender Bassman 100, TE V-type 600h, Mesa Buster 200, Mesa 2-90 power amp.
I liked the Scout cabs with the Bassman 100, they seemed to fit well together tonally. Lower powered amp that is not voiced too bass heavy were probably the best matching points here.
The Trace sounded ok with these cabs, but I ultimately decided that I just did not like the hybrid 600 tone in general so I sold it.
The Buster sounded good through these cabs, particularly with the lows under control. Very punchy and tight. Also sold the Buster for other reasons.
The Mesa 2-90 sounded GREAT through the Scout cabs. I ran one cab on each of the outs, and used the amp without a pre-amp in it's stand-alone mode. This amp was just a loaner for me, but it sounded very good to my ears. it was a little bit of a goofy set-up with the 2 outs and all, not very giggable in my mind, but still ..
very nice tube sound.
As far as buying a used Walkabout, if I could try it to make sure it worked, I would have no reluctance buying used Mesa stuff. Mesa gear is typically built for the long haul and hold up really well over time. Mesa also has a very solid 5 year, user transferable warranty, so that helps the confidence as well.
good luck