i have the same items, except i also have the venta mx and a patagonia nano puff, im currently trying to re vamp my system, but having a hard time trying to put the right stuff together. I think i am going to go with a smartwool micro weight wool t shirt, and then the r1 for my base layer, followed up by the acto. Im thinking for high output even down to about 15F that should be a good set up. After that im at a cross roads. Do i keep the venta mx, which layers fairly nicely over the acto and the r1, or return it and add the atom lt, or the nanopuff for my next layer. I was thinking of getting an atom SV for rest stops/belay jacket in moderate temps. let me know what you think. The ACTO fits fairly snug on me, so layering anything besides an r1 under it is probably not going to work too well. Anyone please chime in for some suggestions...?