But if I play objective or campaign I expect to respawn.
And to have multiple objectives.
And a bigger map.
The way I see it only the first point is a possible sticking one.
Multipe objectives is not set in concrete anywhere. ET maps can have as few or as many and people adjust.
Map size is ‘irrelevant’ in as much as some servers only run smaller maps, some bigger. Depends entirely on the server admin. Personally I think there’s a ‘market’ for smaller and simpler ET maps, and am considering doing Lord of the Rings mini-map spin-offs to cater for it - not everyone likes to play on a 15+ player a side server. Smaller maps make for great training maps as well, so clans are more receptive to them (if done well).
The respawn thing… yeah people will expect it, but you can always put instructions as to what happens in the loading screen, limbo screen and do announcements at map start (kinda what I now do in helmsdeep to say how to use patrol points).
People will soon pick it up. OK you are doing something slightly different, but if you could get it to work identically in both objective and stopwatch mode then that surely seems simplest?
Just thought of a problem with LMS mode actually, and can’t remember how this is handled in CS. What if the attackers plant dyno but then all die? Is this an automatic defence win, or must they still defuse? I think it makes more sense to have defence have to defuse, but of course LMS mode won’t be able to deal with this 
Seems like it’s not possible to have it work identically in both - up to you though which mode suits it best. From this problem alone I’d say LMS now looks the less attractive of the options.