Kino tubes can last for thousands of hours. They fail more from physical abuse than from excessive burn time.
Each tube is about half an amp so you can plug many units into a household circuit before you need work about blowing a fuse. This is one of the main advantages of kino flo lighting.
Finally, color temp will not change significantly because of use, other than to say that it does change as the unit warms up and gets hot. For that reason you might want to re-white balance after the lights have burned for an hour or so. Diva's do have a tendency to burn green (and different than conventional Kinos) so many folks who like to shoot at preset white balances will often use a small amount of minus green (magenta) gel to compensate.
Are you planning on purchasing or renting Kino's. In the mid 90's I was the Gaffer on the Profiler for NBC and we had a large set with more than 50 kino flo's and at that time the owner of kino was constantly trying to produce more lumens and the ballast kept changing every year and the rental houses would test the lights for rental by simply turning them on then off and what I found was 50 lamps that changed color temp by the minute and the DP and I would just sit back and watch it happen. I felt like a meter maid. My point here is if you are renting order a few extra ballasts and tubes, as the cathodes at the ends of these tubes over heat and it may not be seen by the $8 an hour shop tech who is testing them. If you are purchasing I would only recommend the T12 units, why? because these compact tube units IMO have too many sources and poorly design reflectors and they defeat the purpose of the original design. That is why many DP's must use diffusion with these lights to blend the tubes as one source. And if you are purchasing I wouldn't recommend purchasing anything but new units.
I just don't like multiple T-5 tubes that continuously wrap back and forth creating multiple sources. Just not a fan of this type of tube, and they have never IMO really ever matched the original CRI or Kelvin readings of their original T-12 tubes.
I like T-12 or as I have built T-8 (dim able) units with properly designed reflectors to magnify the single source double ended linear tubes. And yes wrapping a layer of diffusion can remedy the diva for my needs. I don't own or order the diva units. I do understand that Kino has found it much easier to dim these types of tubes that adds a nice feature to the line. I'm in no way trying to discourage anyone away from these diva lites, I'm just stating my personnel opinion.