The general in this race is going to be close. I really don't know who has the best chance to win among the Pubbies, because other than Bilbray I don't know them well enough. Bilbray is a bit of a beta type. It is a mistake to always assume the most moderate Pubbie will be the strongest candidate (as I am sure you will agree :) ), even in a somewhat moderate district, which it is now, like this one. Presentation counts.
I'd have no problem with Bilbray if he wanted a rematch with Susan Davis, I just think he is a poor fit for this seat. I prefer Kaloogian over Morrow, but both are good men. I don't know what is the deal with Roach, and I tend to be very wary of rich guys coming in trying to buy a seat in a seat that doesn't require buying (if he wants to do it with a Dem-held seat, again, be my guest). The two Republicans that come to mind that did that were no gems, Darrell Issa being one, and Michael Huffington being the other (and his little stunt ended up turning a safe GOP seat into a Democrat one).