Most crits come from pistol-like calibers due to spam from smaller vessels and convoys, but those can only shoot at the first line they oppose. So if your intent is to use FCs on BB/BC/CA and you have those screened, reliability hit is not that crippling, while +15% Heavy/Light attack and +20% AA (effective gains compared to 0 lvl FC) are significant. Besides, it just feels 'right' to have advanced computers at advanced ships!
Also, given the crits nature, it doesn't make that much of an
operational difference to get 2 or 3-4 crits [provided every other input equal] - post-battle, you're next to disabled either way and would really want to remove those crippling -80% speed or -50% turret damage in any case. Apparently, sometimes you'll get a very different outcome with reduced reliability, which indeed would negate all the benefits you've got over time, but the truth is it's even tricky to test it properly to get a 'solid' (non-gutfeeling) evaluation, as every test is bound to be synthetic.
Unfortunately, this game severely punishes you for trying some both historical and logical ways of conducting naval war by commiting pure capital groups, who in real practice would just outrun subs and retain far better ocean seafaring than destroyers, while in HoI4 both these classes magically 'catch' 40'000 ton ships in the middle of Atlantic or Indian Ocean. Or where do these destroyers get fuel from to be ready round the clock, I don't know.
I.e. in one of my last runs I licensed Pocket Battleships (whose sole purpose is to surface raid) off the Germans , built a couple of those to access too remote areas otherwise, and my ships would still get a [#$@$] of crits with FC0 because apparenly convoys never gave up without a fight.
All in all, yes, now as the penalties are halved I'd say it's worth it as the tech is cheap and so is the production. Besides, you do get less crits from the enemy if you sink him faster
