tadpole
i used a citizen aqualand watch for years and only sent it to the company for replacing batteries and pressure testing once. the reason was this: batteries themselves are ridiculously cheap (couple of dollars), the bill for the above was somewhere around 80 usd. might be different elsewhere, of course.
but what really annoyed me was the fact that i didn't get any proof of the pressure testing, which for me as a diver is, of course, important. i don't care about the guarantee when i take my watch on a trip to egypt or asia for half a year and it starts leaking there.
i worked in a dive shop and when we were pressure testing computers or dive watches we put them in a wet pressure chamber the size of a bucket and went for a dive to 70-100m. we'd compare readings with a 2nd watch/computer and then decompress the thing. that meant that the watch/computer, when returned to the owner, had one dive in the logbook. the test dive.
now when i received my citizen there was no dive in the log book. i tried to get information from my local citizen dealer but didn't get any information on their procedure.
maybe they replaced the batteries after the test dive to clear the log, maybe not. anyway, i had no proof that the pressure test was done.
so in my case all i had was a watch with new batteries. i found 80 bucks not worth that, of course.
for 5 years i replaced batteries myself with no problems whatsoever. take care of the o rings and the screws and you should be o.k.
just my idea.
regards
roland