I have read from one source that the short magnums are not suited to taking these very heavy bullets due to the amount of space the shank takes up inside the stubby cartridge.

Is this true or has anyone used the 220's or 250's in the short mags and can comment?

I haven't tried, but the magazine on my model 70 300WSM will load out to 3.1". That should leave you plenty of room to load bullets out to rifling length, which will help with the powderspaceissue (which is overblown marketing hype anyway, IMHO). Even if you lose 3-5% usable volume, you are still shooting a powerful load.

I wouldn't let it scare me off!

If you fall victim to the marketing hype and buy one of these short fat MAGNUMS don't dispare. You still can load those heavy bullets so they will come out of the barrels fast enough to do some damage to elk size game even if they are a pityfull design.
They really are a case of the four shorts; short case, short neck, short throat and short sighted marketing.However, it's usable. roger

I found the useful weights for the Remington 300 SAUM to be from 110 to 220 grains.

The WSM from 110 to 250 grains.

Unfortunately I have not yet worked-up the WSSM.

In comparison, the .300 Winchester magnum was from 100 to 250 grains, the old and tired .30-06 was from 57 to 250 grains, the Remington "Ugly Mag" was from 110 to 250 grains.