Hard to say about the installation. I certainly read some stories early on about parts shooting across the room and technicians having to come back a second day to finish the job, but I think they have significantly improved the installation protocol since then. Believe it or not, I have the first set of directions from HP from when these were still beta parts and they suggest a cap from a Bic pen as an alignment tool. I believe they now send an inexpensive custom installation tool with the parts, as well as a few extra rollers and plastic carrier brackets. It only took my field tech about an hour to do. One advantage of having them do it, though, is that you may get lucky and have a tech like mine that requests a pinch roller alignment tool in addition to the roller upgrade kit. It is a milled aluminum block that makes sure that everything is parallel after pulling it all out and reinstalling it. It aligns the black plastic carriers that support each roller on the track they mount on. Mine proactively researched it and ordered the part on his own. If you ask about it, you may be able to have a tech show up with one, too. I don't think it is necessarily required, but is a nice extra measure of safety.
Keep us posted on how it works out for you.