I had a set of Rails in my Tele and I just recently swapped them out. As far as a hot humbucker sound goes, they are about as good as it gets. I wanted a more Tele like sound, so I went with the Lil-59's set to replace them. The Lil-59 is not my favorite. In series mode, it is rather dark, but I like how it feels to play. In parallel mode, it is just off, it thins out and gets brighter, but the feeling goes away and it verges on too peaky or chirpy. I will be on the hunt for another bridge pickup soon. I have a Jerry Donahue in my other Tele and it is the SHIZNIT, hands down the best Tele pickup ever made. As much as I would like to have one in every Tele, I like having guitars that all have their own thing going on. 
Back on point though, the Hot rails are a very good all-around pickup. I used them in parallel mode as well and they work very well that way. They get brighter, spank a little, and get a little chirpy even, but they are really more suited for series mode. I won't get rid of them if that is any indication. I just need to get another guitar to put them in 
