[quote name='MisterFingers' timestamp='1368977158' post='2083599'][size=4]I want an electric sound that is different from the J, but still weighty in the bottom end for an upright -ish tone[/size][/quote]
Bit late, but here goes anyway. I have had a Spectorcore as a backup fretless. With the combination of the HZ pickup and the piezo bridge you can dial in a very upright-ish tone. I was quite surprised with that, hadn't expected a Spector to sound like that. The semi-hollow is not an issue with resonance or whatever, these are not true acoustic basses, rather "chambered". Closer to solid body than to full acoustic. Well made, good value, all IMO. I'd still like to own a 5str Spectorcore some day for that upright-like tone. No complaining here though, as I now have an ACG fretless 5 string J-type. Highly recommended, and Alan is a top bloke.