From what little research I've already done on the Pila 150s series rechargeables, two of the P 150s' should work as a suitable replacement for the three lithium 123's in the SNII. If I recall correctly, a pair of 150s' are just a bit longer than three lithium 123's, but the tail spring in the SNII has shown itself to work favorably with the Pila setup.
-Jim
Edit ...just an afterthought on this topic... I typically get close to what I estimate to be 35-40 minutes of total runtime on my SNII with a trio of 123's. It's one of my most used lights, so I figure we're thinking along the same lines and I may just make a nice little investment in the Pilas as well. /ubbthreads/images/graemlins/wink.gif