I've owned my HRX217K2HMA (the electric start version) since April, 2010. I love the performance, but somewhat troubled by the reliability issues encountered. But to be fair, I do put a lot of hours on it per week with an acre+ that I enjoy doing with a walkbehind rather than my tractor. Exercise program for older men!
1) Hydrostatic tranny serviced by dealer under warranty at year 5 (oil change - cold running 'growl' and low ground speed attributed to cavitation). Replacement authorized by American Honda in year 6 as the issues returned the next season. I started hearing something odd the other night, so a little bit concerned about future costs.
2) Electric starter replaced in year 4 (or maybe 5?) due to lack of engagement (pinion not rising up worm gear). I just serviced the second unit myself last night due to the same issue.
3) Battery is expensive! Take proper care of it and it will last a long time, but be prepared for an $85 bill when it comes time. Replacements are available for less if you shop around....
4) I managed to break the handle near the end of last season. Lower right side at the pivot bolt - the weak link spot in the assembly. My property is hilly, with a lot of crazy landscaping details that require a lot of jockeying to get around. This is a near 100 lb mower, IIRC, and the handle takes a beating. I sleeved it with a piece of 1" EMT, and it seems to be holding up reasonably well. A new handle is like a $150 part. Crazy...
5) I'm on my second rear skirt / trailing shield. It has to transition from behind to under when you back up, so if you do this a lot, expect them to tear. I'll be ordering my third one soon.
6) I'll probably need wheels soon also.
7) I do either a blend of bag & mulch or discharge and mulch thanks to the Clip Director. LOVE THAT FEATURE!!! But I hate the idea of rear discharge. So I cobbed together a custom side discharge starting with a piece sold for another Honda mower. Pretty easy and very effective! Now I have my perfect combo.