Are there specific 650b lowers for BOS Deville, BOS Idylle SC, yet?
I believe there are no issues with actual ones, are there? If yes, tell me how you finding it your self. What size of tire do you use and can you make some pictures.
Basically its not only about lowers but the crown. BOS forks have the arch so high so they have "enough clearance" to take 650b wheel. Lowers didn't need to be changed,then. At 650b bos forks the only change is crown is higher to avoid wheel hitting the crown when bottomed out. And offset to make steering better. That's all the magic about BOS vs. 650b
And all old models can do take the 650b wheel. but in theory set your sag properly and add few turns on high speed compression adjuster to avoid going fork through last 5-10 mm of travel! I hardly found the fork to bottom out anyway :-)
Links to more pictures: http://enduro-mtb.com/en/sea-otter-classic-bos-deville-650b/ https://www.pinkbike.com/u/teknorob/album/Liteville-301-Mk11-650B/
Will post some pics soon as I will be doing this for a temp fix, are the changes all in the lowers or to the steerer or crown! Would it be worth just getting new lowers!