Treating grey leaf spot on rye is very, very costly -- much moreso than dollarspot, IMO. Plus, grey leaf spot can overtake a course within a few days -- dollar spot is slower, and more of a "cosmetic" problem. Grey leaf spot is "holy sh*t" i have no more turf problem.
Newer strands of ryegrass actually have actually been developed with an endophyte with resistance to grey leaf spot. the turf is great - relatively versitile in mowing heights, stripes well, and is cheap -- courses here in phoenix overseed with it every year.
drawbacks would be that it can't really be mown too closely, usually not under 1/2" if it's the dominant turf -- so it can't really be used a facility mandating "tight" fairways. It also doesn't cut well -- the tips of it are usually a little rough, especially if mower blades are a little dull.
-patrick burton