Aaron,
I was in your situation about a month ago. I read the wiki and met with a Canon tech rep in a store where we printed the same images, on the same paper, on both a Canon iPF5100 and on an Epson 4880. I realize that it is dangerous to conclude from a few samples and that factors like color profiles were involved but my conclusions were that 1) the 5100 is a well built printer and 2) the difference between the two printers were minimal: they both have strengths and weaknesses.
I was looking for a sub $2000 printer with roll capacity and the ability to switch between photo and matte black so I purchased the 5100.
After a few weeks of experimentation here are my conclusions. 1) installation was easy (the instructions are adequate); 2) the 5100 has some idiosyncrasies that one needs to get used to like the fact that one has to remember what media type was used to create a particular profile and use the same media type in the PRINT dialogue at print time, but that complexity comes from the fact that this is a very flexible machine with lots of options. 3) the documentation for the 5100 is not great but the wiki is an invaluable resource and the community of users is helpful. 4) the support web site of Canon USA is poorly structured (I do not know about the Canon Canada site) but, as suggested in the wiki, I have learned to go to the Canon Europe site.
I am still experimenting to find out which papers provide the best match for the gamut of the 5100 inks but I can say that I am already quite pleased with the results. The only suggestion I have is that, if you are going to sell prints, consider getting the 6100 instead of the 5100: its is basically the same machine but the sale of the larger prints will quickly repay the difference in the initial investment.
Jean