I am a little confused about exactly what you are asking about.

Are you wanting to rechamber the current LTR, rebarrel the current LTR or purchase a new gun in 300saum?

If you are asking about doing one ofthe former two I strongly advise against it. The LTR is, generally speaking, a very accurate rifle asisand if you are wanting to rebarrel itonce that barrel is removed from the action it will likely never shoot the same again should you want to put it back on the receiver. If you are wanting to rechamber the rifle you will also need to open up the bolt face and install a new extractor, and purchase a new magazine box and possibly alter the feed lips on the receiver.

IMHO the SAUM's are not going to be a long term cartridge and I would opt for the WSM over the SAUM. Keep in mind that Remington now loads and chambers their rifles forthe first three WSM's but not the other way around.

AS far as recoil goes my 300WSM is not bad at all. In fact, the felt, or perceived, recoil is less than my .270 Win. This is largely contributed to me building the rifle to fit me as well as it having a Pachmayr pad on it but it is still very mild. My 13 year old son doesn't mind shooting it one bit.