The XPR6550 is submersable (IP57 - up to 1 meter for up to 30 minutes) and it can be ordered for Intrinsically Safe (tested and certified by Factory Mutual, who is -the- standard in this industry in the U.S. Some radio manufacturers will use other companies for I.S. certification).
Channel capacity is up to 1000 channels.
Battery life, with the high-capacity battery, is specified as up to 13 hours, but of course, that depends a lot upon the amount of transmitting and receiving (open squelch) and even the volume level while receiving (higher volume on any radio will result in higher current drain). Also, using channel scan will result in less 'run-time' on any radio, too.
Overall performance of the XPR6550 has been good, based on my own personal use of one for many years, as well as reports from other users in my area.
However, if I was spending the money on an XPR6550 myself, I would spend a bit more and get the XPR7550. It's got a larger, bright, color display and performs extremely well. The XPR7550 uses the same physical 'platform' as the APX4000 series portables. There are quite a few of these units out in our area, being used on analog systems by ambulance personnel, and the users have been very very happy with them. But, I think you're going to pay quite a bit more for an XPR7550 as compared to the Kenwood model that you mentioned.
Whatever you get, I would strongly recommend that you get a radio that meets the IP57 or IP67 rating, for water submersion, if you're using it in the fire service. I've seen too many radios that have been completely ruined, when they've gotten wet (and not submerged, but just wet from standing in the rain and using it).
John Rayfield, Jr. CETma
W0PM