I work for Pierce Engineering, we don't really get complaints with people using our actions. I tell anyone who's concerned that stainless/steel actions will typically handle higher pressures before the bolt gets hard to open. Keeping your lugs lubed and having the full action DLC'd helps. However, you have to be running above SAAMI max pressure to see any issues. I tell people who are worried about it to just get a stainless action. If you run factory ammo or load within SAAMI max, you'll never have an issue.
We have several high end rifle builders who love our actions and they push them hard. I personally haven't tested the same barrel on a stainless action and a Ti action, but it's something I've planned to do. Run both up to pressure using the same barrel, brass, bullets, powder, etc and see where they top out with heavy bolt lift. Heavy bolt lift is WELL north of SAAMI pressures just so everyone is aware.