It's normal for the Autocords to have a slightly faster viewing lens. It helps with focusing and they were not constrained as much by sharpness concerns when designing a viewing lens.
Are you sure the 3.6 is not really a 3.5 in a font that makes it look similar? Anyway, that's a tiny difference in light level, less of an impact than shutter variation. You can ignore it.
I think the Autocords are the best value in TLRs. I had one, sold it, regretted it, bought another. Karl Bryan sells and services them, very experienced, reasonable, and quick.