Agreed that poison doesn't seem to be very useful. Maybe in some off chance where you leave a target with 1 HP after attacking it, but that's pretty rare (especially in GE) and even then, it's a coin flip whether the unit will actually be poisoned. It seems like it was intended as some sort of 'bypass' for Reactive Armor and Force Field, but it's too slow-acting to really be effective. However, that doesn't stop Mantas from hitting very hard and also having pretty high defense, while being a fairly mobile unit as well. Their niche is narrowed rather heavily due to Turturrets being a no-brainer against heavy units, but I think that can be said for most units at this point. Turturrets are almost definitely the strongest unit in OF, but they have weaknesses that they cannot negotiate. Mantas work great for taking out Eels and Dragon Drones, for example, while the Turturrets can take out just about everything else (even Subs, provided they do so before entering Contact range). I believe the time has come for us to start moving past the time-tested 'strategy' of '7 rogues plus 1 other unit' and start pairing two or more units together in a battle. You start to get a better feel of how each unit is intended to be used when you aren't trying to brute force your way through each battle using just one type of unit.
I agree that 7 rogues is mostly dead but that's really all about turturrets and the fact you eat a bit of stray damage if you include rogues... I have yet to use mantas on offense - on defense they are a bit hardier it seems taking 3-4 hits from a hover tank they usually can't reach instead of 2 - but still allows 8 hovers > all to continue to work (or at least it's never mantas that breaks it from working). So OF combat remains extremely boring...
My bigger issue still remains : there needs to be a (LARGE) goods sink whereby either many low age players all will want a set of OF goods for a GB - atlantis museum just didn't have wide enough appeal, or high age players will want to consume all the OF goods they can get their hands on (i.e. what GvG used to accomplish). I'd hoped you'd learned your lesson in AF with orangery saving the economy (which fwiw was an excellently designed building - both useless and appealing at the same time - everyone seems to want one even though most people really shouldn't be spending the space on it) and would have something in OF by now but here i am posting 200 OF goods for 100 AF goods and regretting ever having entered OF which in turn makes me not want to play my lower age cities because what are they progressing towards - ultimately a dead end or misery - why bother?