Jason and I talked about this at length. There are a bunch of factors that go into tone, and in my case I currently have two basses that sound exactly the way I want them to - that being the RA Deep 4 (34" scale, totally different vibe) and the YYD (34" scale). So the for the spec on the new twins, we started kicking around the various factors that go into the equation, some of which have been argued ad nauseum on TB:
body wood
chambering
body shape (single cut vs double cut)
neck wood
fingerboard wood
neck construction (dovetail vs neck-through)
pickups
scale length
I know that I like the YYD which is 34" scale, chambered walnut body, maple neck, ebony fingerboard, dovetail, PJ. The new basses are 5-string (at least so far

) and one will be fretless so that has to figure into the mix. I know that I want 17.5mm spacing as I prefer that on 5-strings. I also want 24 fret equivalent as I want some room between neck pup and end of the fingerboard. So then it comes down to the details. Some are easy:
ebony fingerboard - I love the tone, better than pau ferro or Braz rosewood for my needs.
walnut body - love the tone and the look
17.5mm spacing - better for me for chords
small frets - personal preference
Beyond that it starts to get fuzzy.
Body shape - Originally prefer the Monarch aesthetic and that can be chambered. But the MG shape is growing on me, and my Rob Allen is a single cut so I'm used to that as well. Plus I think the single cut influences neck stability.
Scale length. The MGS is incredibly comfortable to play. But I have two 4-strings that are keepers that are 34" scale and there is an argument to be made for having everything a single scale length. Especially since 2 of the 4 basses will be fretless. Plus all other things being equal, the longer the scale length, the more piano-like the tone.
Neck construction - the Monarch 5 experiment was interesting but I'm not hearing huge tonal differences between dovetail and neck-through. I find neck-through to have a bit more comfort up high, but I love the aesthetic of the dovetail. The tops I've picked out are non-solid, so if I went dovetail I'd have to pick new tops. I'm leaning neck-through at this point.
Pickups - I love the P pup. Jason is checking to see if the EMG PJ5 set will work with 17.5mm bridge. If it does, that'll be on the fretted, no question. For the fretless Jason prefers the dual coils and I can understand that working so no worries there.
One downside to having so many choices is that you have so many choices. Luckily Fodera crew have built a few basses and know a few things. And Jason is a patient guy who wants to get it right.