Hi Theo,
Welcome!
I purchased a Canon IPF5100 in 2007 and had a great experience for 5 years. I ultimately scrapped it after the circuit board needed replacing which was far more expensive than the printer's residual value (and I was concerned that it may fail again after investing in an expensive repair). I ended up purchasing an Epson 4900 as a replacement in 2012.
A couple of high points - the printer was very good in daily use and paper handling as well as very efficient with ink. Even if I didn't print for a period of time, it fired up and worked very well. It made beautiful prints - which is the most important criterion. The canon software driver and photoshop plugin gives you a fair amount of control.
Before I go any further, a note of explanation is in order. When users say that their Canon printer never clogged, you have to put this into context. Canon and Epson use different approaches to managing ink head clogs. An Epson printer is expecting that all nozzles are clear and therefore careful printers need to have a fully clear nozzle check pattern before they print. Canon, on the other hand, automatically "maps" clogged nozzles and "prints around them" so in effect, the nozzles are clogging but you don't experience it until so many clog that you have to replace the print head ($500 each - the printer takes two). The Canon printer is designed so that the print heads are user replaceable. Epson is not designed to be user replaceable.
Back to your decision. I gave you some positives before; here are the negatives. 1) the printer technology is almost 10 years old. While the prints were, and are, nice, the prints made with my Epson 4900 are noticeably better to my eye. The newer epson produces prints with more gamut and more subtlety. The prints made with my Canon look very nice until I compare them to my Epson 4900 prints! The difference may not matter to you. 2) Not sure how much effort Canon is putting into keeping its 5100 printer software up to date - you should check this. Photoshop and Lightroom continue to progress - the fact that Canon has not entered the 17" pro market with a new model since the 5100 indicates that they have de-prioritized it. I would do some homework here. 3) Ensure that there will be a steady supply of print heads - My guess, though I could be wrong, is that Canon ceased production of this printer some years ago - not sure how long they will support it. I have seen "new/old" stock sales of the printer from online merchants in the US.
Of course, there are other options, but you did not ask about those so I will not walk through them.
Net/Net - it is a solid printer that should serve you well. However, the print image technology is 10 years old and Canon does not seem to put much emphasis this model any more.
Best of luck with your decision.