Rondo is considered by the rest of the league to be a top 3 point guard...
I chose to quote Screwedupmaniac not to pick on him as he is pretty much saying the same as everyone else although I am not sure how he could substantiate the statement that I highlighted above (more on that below).
I will also say that I think Rondo is a very good player but overrated on this board. The main thing that I don't think people take into account to the degree it should is the impact of his defender playing 10 feet off him. That makes everything harder for everyone else on the floor. Rondo gets his numbers but everything else bogs down. That wouldn't happen with Billups.
Also keep in mind that there is one person whose judgement I trust who made a very clear statement that he thought Billups and a couple of other guys were better than Rondo (and certainly not top 3) and that would be Coach K. Now don't jump all over me with the arguement that the Intl game is different. I get that but I don't think you can discount what Coach K was saying by who he chose for Team USA and why.
And finally, Billups was the best player on a championship team not too long ago. I believe he would be better than Rondo for this team for the next few years; in fact I think it would make us the favorite. You can say oh what about defending Tony Parker (for example) but what about Tony Parker covering Billups?
The problem is after those 2 years, then what. You give up quite a bit of the future but I think I would do it and I don't think Jsaad or the idea is stupid nor do I think Coach K would.