I think base selection depends on the action. Things like the strength of the action and the length and size of the load port I think can make a difference. For me, I prefer the one piece. I have a feeling it supports the scope and rings much better and puts less stress on the scope tube from firing and for the reasons already described. Ive heard of scopes absorbing so much tension from poorly aligned scopes that it ended up bending the tube. That's the last thing I would ever want, so Ill invest in a strong 1 piece base and good rings.
On the other hand when ever I go to gunshops they keep praising 2 piece bases as the be all and end all by saying some nonsense about not having enough room to load a cartridge into the port or some other nonsense. Bullarchy.