The benefits and drawbacks of behind the mast furlers have been discussed in other threads. You may want to search for them if you are considering going this route. Here's one: Behind the mast roller furling - SailNet Community
Briefly, the pros are ease of handling the cons are loss of performance.
One primary difference in the CDI system is that they are using a CDI furler.
Pretty much any furling system can be used for the purpose.
I do like the fact that they have compiled a complete package including the parts needed to modify the gooseneck and backstay attachment. And for a pretty decent price too.
I wonder about the durability though. I have a feeling that this system would work best on smaller, (25' to 30') boats. On the ones that I have installed we modified the gooseneck rather than simply mount the drum assembly above the boom on brackets.
It would probably take a rigger a good 8 to 10 hours for the installation I would guess.