I have a 270WSM and like it. I have not hunted with it yet so I can't tell you how it'd do on elk, moose, etc. Recoil is manageable. You may get a lighter rifle and end up feeling the recoil a bit more than with what you've got, but I don't think it'd be all that much.

You're likely to find ammo availability a bit frustrating. I have, maybe your area is a better. Certainly not as widely available as your 270 or 308. I'd recommend checking out your local stores, see if they're likely to have what you'll want/need. Better than being frustrated later. Price is comperable, just a few dollars more a box than the equivalent 270 ammo. I've gotten around that by buying mail order in bulk, saved some money that way. I'm getting set up to handload, so ammo availability won't be a problem much longer.

I'd go with the 30-06, so that you can shoot the heavier loads. I don't know that the WSM gives you THAT much over the standard round to justify having two 270s. That being said, you've got the middle ground covered with your 270 and 308. As you pointed out, it's not until you get into the 180 grain bullets that you start to see some differences. You've stated that you don't want to go the the heavier magnums. Maybe you should reconsider. What you've got can take care of your medium sized game/pleasureable shooting needs. Taking a bigger step towards the 338 or 375 would give you enough gun for the big game that you'd probably hunt less frequently.