What can of tone can I expect with MM-style HB in bridge and Jazz in neck? Looking for big rock tone but want to retain some attributes of jazz tone. Worried that PJ setup will be too punchy or too bright.

Lakland 44-02 (4-string) or 55-02 (5-string) has that configuration, with a tremendous variety of tones. They're outstanding basses, extremely well made, but pricey, though -- around $700-800, used, or a little over $1k new.

Here's a link to the 55-02 on the Lakland website:
Lakland 55-02 (http://www.lakland.com/55-02.htm)

MM/J configuration is not unusual. I'm sure others will chime in with recommendations of their own. Musicman Bongo is available in that configuration, as well as others.

P.S. I'm in Portland, too. I'm eagerly awaiting a Lakland Darryl Jones 5-string with a J-retro preamp. Should arrive in the next few weeks, and I'll post a review. :D

AppleMusicRow in Portland had a 55-02 a few months ago; I'm not sure if they still have one in stock, but you could call, and maybe get to play one in the store.

Well what would that configuration sound like, broadly speaking (understanding that pickup selection matters greatly)?

I guess my ideal tone would be bass tone from AIC "Would" (albeit that is tone with pick, I believe, and I play with fingers) meets Rush "Vital Signs" or "Freewill" solo.

I will try to check out a Lakland with that config in Apple. Thanks for the info!