Really appreciating all the feedback and info from you all. Very interesting neck profile discussion. Maybe I'm more on the "schooled/classical/technical" end of the technique spectrum because I find the modern C on my Player really comfortable. My thumb position changes a lot based on where on the neck/strings I'm playing, but it always feels pretty natural with the Player. I used to play an Ibanez BTB 4 string, which feels wider and flatter, maybe like a Fender D, and it felt a lot harder for me to play. Seems like all except the really expensive new Jazz basses have C necks? Also makes me really want to try the "slim C" on the Pro II before biting that bullet. Anyone have thoughts on the slim-c vs modern c? How noticeable is the slimming?
So far what I'm gleaming from all this is that the individual instrument usually matters more than whatever model it is: many people seem to be happy with all the models I mentioned (personal preferences). And if I can't find a local instrument to get in person,
Sweetwater seems like a good alternative with their customer service and individual photos. Also - way more votes for the Am Pro II so far.
After all that, the Highway One on Reverb is still calling to me. I messaged the seller and they said there are no issues besides some small dings on the body and some minor fret sprout on the upper frets. Thinking I could maybe offer $900 (asking $980). Then with shipping it'd be under $1K. If I ended up swapping the pickups at some point, I'd still be pretty far under a new instrument. But then again it feels like a gamble on a 14 year old bass from the internet.
Thanks everyone! I may be slow to reply, but I'll definitely post with the end result whenever that happens.