One possible disadvantage of the Seacam and Subtronic strobes having non-removable batteries is the risk that a airline may refuse to carry them.
The problem was highlighted in a recent article in the German magazine "Unterwasser". IATA rules state that a diving light (doesn't mention strobes directly) must have the energy source and the "heat producing element" disconnected. Then it may be carried in hand luggage.
Subtronic have a downloadable PDF on their web site that is a reprint of an LBA (German Civil Airlines Authority) that gives an exemption to the Subtonic strobes if they are fitted with a means of blocking the switches from turning on. Subtonic and Seacam supply a plate designed to do this. However this PDF is in German and doesn't look very "official".
The Unterwasser article suggests that in any case an airline can refuse to carry the strobes. I remove the halogen pilot lights from my Seacam 150 TTLs and am prepared to argue that the remaining flash tube is not a "heat producing element". With my Subtonic mini, I would have to argue that the LED pilot is also not a "heat producing element".
One day this is not going to work and I have to accept that the next strobes I buy must have removable batteries.
Jeremy Brookfield