So, being that I'm as broke as can be, I decided to take a chance and install the Dragonfire Power Rail pickups. Picked up a set of them for $40 on Ebay. Figured at $20 a pickup (as compared to $80 for the DiMarzio brand name of the same pickup) it was worth a chance.
Now that I have them installed, I can honestly say that I'm very happy with them. Not having experience with the brand name pickup, I can't really say that they are better or worse, but they are a huge improvement over the stock Epiphone pickup that came with the Epi Les Paul.
First thing I noticed straight away was that they are loud, much louder than my stock pups. I also was impressed with their clarity, very little muddy sound even with lots of gain. I'm sure I will fiddle with pickup height a bit until I'm perfectly happy with them.
Negatively, one of the pickups does seem to be louder than the other (the neck pickup is the loudest.) Fiddling with the pickup height should correct this to a degree, and it may not matter all that much. But if you're looking for a balanced volume between the two, then you may have a bit more work cut out for you. Personally, I don't mind the difference as it gives me more choices in sound, and I know a lot of players like one pickup to be louder. A lot of this will come down to personal preference.
Tons of sustain out of these pups as well.
So if you are on a real tight budget and want to upgrade the pickups in your guitar, I would give Dragonfire a go. There are also similar pickups sold by GHS (guitarfetish.com) for $40 a piece. I suspect the quality control may be a bit tighter with the brand name pickups, but $140 difference in price is huge, especially in this economy.