The fabric used in this is the exact same fabric in the Patagonia Thermal Weight line, which is Polartec Power Grid High Efficiency (HE) @ 3.8 oz/sqy fabric weight.
The R1 is the regular Polartec Power Grid, and is the 6.8 oz/sqy fabric weight, which will be a lot warmer.
I'd say the temp range you mentioned, 50-60 degrees, is still accurate for this 3.8oz weight as an active layer, in case that helps anyone. I've never owned an R1 but I would imagine it would be suitable at 50-60 degree standing around in camp. But with this Rab, using the 3.8 oz HE fabric, just throw on a wind shell and you will drastically increase the thermal efficiency for colder active pursuits or those mild nights in camp.