I'll be venturing into extended subfreezing (possibly subzero) shooting next month in Yellowstone. In the past I've used lithium batteries with good success, keeping several in inside pockets to use as replacements when necessary. However, my Maxxum 9 vertical grip allows me to use lithiums (in the body) and lithiums or AA alkaline or NIMH batteries in the vertical grip, simultaneously (for those interested, in the vertical grip I can use either two CR123's or one 2CR5, or 4 AA NIMH or alkaline - the latter of which has lousy cold weather performance - while still having the CR123's in the body available for use). The question is whether anyone has any cold weather experience with NIMH vs lithium performance, and whether to go strictly with lithiums in both the camera body and grip, or lithium in the body and NIMH in the grip. Thanks in advance for your responses.