I had a Ruger 7mm RM that I sot the barrel out of in about 1000 rnds. When you had mentioned you had done a lot of shooting in yours in the past I was wondering what condition your throat might be in. A 7RM wont last any longer than a 7WSM, maybe a little shorter. A 300 WSM will last a lot longer than a 300 WM for some reason. You might want to get the bore of your M1500 scoped to see what shape it's in just for grins. You might also heve bedding and or crown issues, etc. if you do get it bore scoped make sure you get ALL the fouling out if it first so the smith can get a good look at it.
That being said, I like Senderos. Just bought two used ones in the last 6 months, a 300 RUM and 25-06. Haven't fired the RUM yet, but previous owner said he shot a 3 shot, 1" group @ 350 yds with it. The 25-06 I just took out a few days ago to shoot a group it before cleaning and breaking it in. The owner said it had maybe 200 rnds through it. I set up a target about 110 away and set up my portable bench but forgot my chair so I stood and leaned over to shoot it with bi-pod. It was awkward and not real steady and had a blurry Tasco scope on it which I could barely make out my POA with. After a sighter I made an adjustment and then my next 3 shots measured .24". The fourth took it out to .45". I am a big Sendero fan. Great out of the box accuracy. They are just plain built for LR shooting with heavy barrel and aluminum bedded stock.
Have read a lot of good things about Savages, but I like purdy guns
Tikka's have a great rep for accuracy. I have a friend who has a T3 in 270 WSM and shoots 1/2 MOA with it.
On barrel life.... there will always be trade-offs when it comes to performance. The farther you shoot/hunt the bigger a cartridge you will need to be confidently effective. That's why I have a 300 RUM. I am expecting less than 1000 rounds from it but hoping to get more with a good break-in using a bore conditioner. In anycase, I realize up front 1000 rounds for a 300 RUM is a good life. It will out range a 300 WSM by 200 yds, a 30.06 by 400 yds and a .308 by 500 yds, all of which will have much longer barrel life. If I put 200 rounds down it the first year including load development and another 100 each additional year for practice, it will last me a while. I can shoot the 25-06 for fun and trigger time.
Recoil can be mitigated and dealt with, with or without a brake. In the field, recoil will be un-noticed, especially for only one or two shots when adrenaline is up a little.
My vote is for the Sendero, Tikka next. If you go with the Tikka, I would get the 300 WSM. Much better barrel life than a 7RM and about the same range but a little more thump with close to the same recoil.
One other thing... shooting different loads, i.e., differnt powders and/or jacket material without cleaning between load types can affect accuracy.