I'm not a 49ers fan, so maybe you guys don't want me answering
but my answer is no I don't think they should pursue Peyton. I think the growth in Alex Smith, both in his play and maturity was so profound, you don't mess it up. You continue to build on that chemistry that this team had in 2011 and you go for another run. This team will most likely not be challenged at all in the West this year and that should mean another division title and possible first round bye.
If you sign Peyton, you slap Alex in the face. You also risk losing the cohesiveness built by the team last year. And how healthy is Peyton?? What if you sign him and he gets hurt?
Too much risk involved if you ask me.
BTW, FWIW I'm a Cowboys fan, and yes I'd sign him in a heartbeat