Originally, I was going attempt to tie in the PA primary with what happens in Utah primaries, but I guess I forgot that thread after I got hung up on the way the D-News got its "scoop."
So enough meta, my point is this. Primaries aren't always good or bad things for parties. It depends on the situation. Let's take the biggest primary race ever: Clinton vs. Obama (I say ever in terms of real dollars raised and spent, as well as votes cast, etc.) This race has been good for the party, but the lull between Missippi and Pennslyvannia caused things to get snippy and not helpful for the party. Swing counties in the 'burbs of Philly, like Bucks County, became blue as a result of this hard-fought race. That has to be good news for the party's chances of winning the Keystone State in November, even if Obama loses it big today and becomes the nominee. Voter registration and participation for Democrats has gone through the roof this cycle. My favorite statistic has to be that more people voted in the Texas prima-caucus for Obama and Clinton than voted for John Kerry in November 2004. Turnout appears to be high today, repeating a pattern from the other 40-something states.
Other times, a primary is destructive. The U.S. Senate race in Oregon seems to be an example of that on the Dem side, while the 2006 Senate primary in RI on GOP is another example. When primaries get personal and nasty, both candidates look worse. Another way this can happen is if it is ideological and the incumbent is hanging onto a district based on his or her personal connection to voters alone. This is the danger in MD-1, where moderate Republican Wayne Gilchrest was outsted by a Club for Growth candidate.
So would it hurt the GOP's chances in Salt Lake County to have primaries or go to the convention? Conventions to me seem relatively painless for the candidates if nothing embarassing like stalking charges or insane statements come out of it. Because if the attacks are just between activists, regular voters won't even know about it. For my sanity, I wish Obama and Clinton would just conduct their daily phone conferences with the remaining 300-or-so superdelegates and leave the rest of us alone.
Primaries are a chance to test out GOTV operations, messaging, train campaign workers/get experience as a campaign worker, and get to know your base voters. So as long as the potential pitfalls of primaries can be avoided, I think they are a good idea.