Either one sounds good to me, I'd rather get rid of the RINO and at least run an honest conservative and lose. That way you are at least offering people a choice, and building momentum for the future. With a RINO, you think you've won something but it turns out to be a steaming pile.
With a reasonable Senate majority like we have right now, 55-44-1, this is as good a time as any to jettison a few RINOs. Maybe some other ones will get the message. Most of them don't hold strong convictions anyway- if the price is right, or the danger too great in acting against the Republicans, they can always pretend to be conservative.
Unless there is a conservative in RI with a real shot at winning (HIGHLY unlikely) I think I'll stick with the RINO in that race. You never know what might happen elsewhere and a RINO's vote towards a Republican Majority Leader is as good as any conservative's.
There is no upside for Chafee by switching parties, unless his switch gives the Dems control of the senate.