Just my experience...have a 48" 4x54w Odyssea T5HO over my 55g planted. Now I've not had it a long time (couple of months) but it doesn't run hot. It's quite cool when I just run 2 bulbs, when I do a mid-day burst with 4 bulbs it's warm but nothing uncomfortable to the touch.
I have a Coralife 30" PC fixture on my 29g. It runs much hotter than the Odyssea. I've also had the same fixture fail after less than 2 years of use. I only bought another one because I was in a bind and didn't want my plants to die. It was what was available. I do not plan on purchasing any Coralife fixtures in the future but may purchase another Odyssea.
Also, I have a friend who had a Nova Current fixture catch on fire. So I'm not convinced it's simply an Odyssea problem. I don't run my lights when I'm not home though, and I check the fixtures often. I did try the Odyssea canister filter a couple of years ago and it did leak after a couple of months. I ended up throwing it out.