Hey Stan, great to hear there's another manufacturer ripe enough to join the 29" movement. I'm with Ibis-SS, very mature of you to come over here and ask opinions rather than try to figure it all out by yourself.
48t rings, those are not REALLY necessary. Perhaps if you were to build a Hybrid bike out of it, and you're the type of guy that only wears out the 11t on his cassette, because of his ultra-slow flatland riding style. I hope that only occurs here in Holland, though. Making the maximum 44t, you win a little bit in the chainstaylength/tire clearance department.
Definately be disc-ready. Make the bike look disc-only by using the optional Cantimounts VooDoo uses, which simply bolt on there. I like the look of that, some DJ bikes have it too. Sell the cantimounts opional, if that helps to cut down the basic price.
The Eno is quickly gaining acceptance. One thing you could do if you're making the bike geared-specific, is to make some popular Eno setups work out nicely, with a chainstaylength that works well with various gears in eno-mode.
If you want to do well in the magazines, a KM-like geometry, minus 2" of seattube, is bound to get great reviews. Right now, 29" bikes are still competing with 26" bikes, so they have to be a like steep on the headtube (no slacker than 71,5º headtube unless for a really small size to avoid toe overlap). If people want a more relaxed steering bike, they can just add a 100mm travel fork.
There's room in the market for an aftermarket ridig fork for sure. The KM set the standard in rigid fork geometry for 29"ers, and is liked by everyone, but curses by everyone for it's harshnes, and by some for it's weight. If you can make an affordable, around 2 lbs , 468-470mm rigid fork that doesn't try to brake the rider's hands, many will get one aftermarket or along with their Soma frame.
No more than 68mm of BB drop, on the KM that's been okay for the vast mayority, but Fishers that passed the 70mm barriers, got bad reviews for it. Stay between 55-68mm accroding to your beliefs, and you're ok. Personally, I'd keep them pretty low, stability is one of the main traits of 29", why take that away?
Definately make sure there's a full pound between your own offering and the KM. It's doable, and the psychological diffference of a full pound could persuade many riders to give your offering a closer look.
If you need loooong chainstays to make the 2.35" tire fit, slacken out the seatttube angles on the larger sizes a bit to compensate. People coming into the 29" sport probably like short wheelbase figures because they think shorter is better, and 29" bikes don't need superlong chainstays anyway, as the higher placed axles help a lot for steep climbing.
Ddi you ever see the adjustable chainstay length frame posted on the SS forum? If looked to be a cheaper solution than an EBB, and really simple, too. Not sure if there's a patent on it. Some bolts in grooves allowed for chainstaylength adjustment under the BB. Very long shot, but it could be an option for a SS-ready bike that doesn't require the Eno.
Many tall riders around now, see if you can make the largest size a 21.5" or 22". Riders for that size won't have much standover problems anyway. Only being 20.8" is the main problem with my Fisher.
Hope any of this helps, good luck!!