the bridge pickup could sound on the brighter side if the bass is maple or spruce. if mahogany, it sounds much closer to the neck pickup, not bright, but still a *touch phasey/nasaly/bridgey...with the tone set at 10(that is to say, quite good). plus u can switch it to the bisonic. I have heard (and played for a moment) Frono's bass, and would not consider it bright. It sounded like a bisonic loaded mahogany JS-1, to me. Novak really nailed it on these pickups. the Dark Star in the bridge position sounds absolutley wonderful. I'm not sure that any tonewood could change it so much? but I don't know.
I have owned two Hoboken SF-2 basses, both maple sunburst, both with original Bisonics, one pre suck switch and one post suck switch. On both of them, the OG Bisonic was noticeably brighter on the bridge pickup (but still very warm and punchy). I am no professional, but it seemed like one would only use that bridge pu higher up the neck (it sounded great if I was playing past the 12th or 14th fret zone!). But I honestly like the look of SF-1's better, aesthically, and sold my SF-2's. Then when my M-85 came along I sold everything else.
In your scenario, I would wait until you recieve the NS M-85 and play it for a few days with the NS pickup (if anything that pickup sounds a little light, or bright, or both...but u can find a sweet spot on it with the tone knob and your amp). So play that and see what you think. Feel it out a little. You may decide you just want a neck pickup and that is that, in which case I give u full LTG clearance to mod that thing into an M-85-II. You may not need to do that, but if you do, you only need the Bisonic in the neck and Dark Star in the bridge, not the pull pots. That is what I should have done with my GSR M-85-II, which I am actually back to troubleshooting again. hoping it is just the pickup selector switch. otherwise it's extraction #3 (or is it #4?)
Of course if u *must have the pull pots on a double M-85, the NS is much deeper, and if u cut in a neck pickup, than for the luv of anything and everything that is good in this world, please just cut in a back door!
For me it just seemed like the double wind BS/DS was worth the extra $40 per pickup, which of course on its own, or in a different bass, that is not the GSR-M-85-II, it obviously is...but for me it was something I just was not experienced enough to see that it was too much. It will be nice when it's all sorted out, and it could have been easier from the beginning if I really thought it thru. But if I *really thought it thru, I would have just gotten one Bisonic (neck) and one Dark Star (bridge)
I will say I have had full use of the neck pickup the entire time, both BS and DS, and that sounds glorious. when I tinker and get the bridge and middle, it does all work flawlessly. but bridge and middle keep going silent. praying it is just the pu switch, or the connection at that switch. honestly might be while before I address it again. but i will