packrat12
Contributor
Stuart's point about needing two for two dives (as opposed to one light and a backup battery) is the obvious con to sealed lights.
Not sure how the OP will be diving, he is Tech level. Most of the time, I am getting 1 tech dive per day anyway. It is an issue that must be thought through. I know I have never used up the time on a 2 dive semi technical dive. The only time I have done it is going twice in 1 day for a longer duration technical dive. In South Florida, most ops limit you to 2 hrs per boat ride so to do that, I took 2 rides.