I have shot a lot of both and now with the onset of neck trouble am very concerned with recoil. The recoil numbers you calculate on the various web sites I think are pretty good (based on rifle weight, bullet weight and powder capacity, etc) and in my experience once you get the calibration of the numbers to your desired recoil limit they are a good indicator. My 270WSM is 2# lighter than my 270 Win (5.75 vs 7.75#) and as the numbers indicated I no longer want to shoot that rifle, even with a sand filled sissy bag. I have a really heavy 30-06 Mauser and the numbers said even with the 180 gr it would be close to the fairly light 25-06 with 120 gr that I can tolerate and indeed it's not bad.
Don't know so much about muzzle blast as in my experience anything with a reasonable barrel length 21" or more it is not an issue, but again I have limited experience there.
