Idk about the [UEF T2 Destroyer] Valiant change - it definitely needs a buff, but I'm not sure HP is the way to go. It's biggest drawback is the poor range of its main gun IMHO. Yes, it has bad torpedoes, but you can easily mend that slightly by say increasing the range by 5 and maybe making it's sonar as large as it's torpedo range (so if you are roaming with them, they actually start firing on subs as soon as they are in range, rather than half-way in, effectively making their superior torp range meaningless).
As it currently is, torpedo-wise, 1 Valiant dies to 5 T1 subs with 1 sub almost full HP left alive. A Salem kills all of them with over 25% HP left (and it already starts off with 1k less HP). It has 40% DPS with torpedoes of the 2nd worst Destroyer, and Salem has over 3x the DPS. I think there's space to make it's torps the same-ish strength as other destroyers have (say 50-60 DPS). Or maybe bolster it's torp defense (indirect HP increase).
But yeah, back to it's main problem. It's the range on those main guns. Yes, it has highest DPS, but only by a little (274 compared to Uashavoh's 250 - 2nd highest). The difference in DPS gun+torpedo is still on the negative for Valiant. So Salems can outrange it, and you can effectively kite with them, and on a say 5v5 matchup (no. of destroyers, not players), you can whittle down at least 1 or 2 Valiants before actual engagement, and as soon as Valiants get into range, Salems can move in and use their total higher DPS (330 vs 304) to end the fight. Exodus can employ similar strategy, theirs being weaker if you micro, but stronger if you don't/the enemy does (since high alpha really rewards shoot-and-scoot tactics, even with minimal micro by the enemy makes it even stronger). Uashavoh's have the advantage of not missing their shots like the rest of the 3, and it has marginally less HP than the Valiant (<5%), which is countered by evading 1 salvo (not to mention going underwater and just torpedo-duking it out).
So if you look at every Destroyer's main weapon:
Valiant:
+bit higher DPS
-range
-somewhat easy to dodge
Salem:
+range
+no overkill
-less HP
Exodus:
+range
+high alpha + AOE
-somewhat easy to dodge
Uashavoh:
+can't dodge his cannons
+can dive
+no overkill
-range
All of the destroyers except the Valiant have 2 '+' and 1 '-'. And on top of that Valiant has piss-poor torpedoes.
Some argue "Well, that's why the Battlecruiser exists". But that's a no-argument for me. Battlecruisers are indeed amazing. But they are only slightly less expensive than Battleships. And while they do have very nice damage and you can't dodge it, they are still out-performed by Battleships IMO. And after a fight, you can actually use a Battleship to threaten coastal bombardment, while the Battlecruiser has the same reach as Salem or Exodus, assuming no one built a sandcastle on the beach that day to block the laser - so in the end, it's only effective in water, vs naval units. But even then. If you have time to build a cruiser, the enemy will soon have a battleship of their own - they are only slightly cheaper (1 destroyer difference in mass, even less compared to cybran). And while a battlecruiser might be much better at clearing out the real fodder, the frigates - don't make the destroyers take the role of cannon-fodder, when there's much more efficient solution already. Battlecruisers won't save you if you are losing (slow to build and expensive vs a destroyer spam), and they are kinda sitting pretty doing nothing if you are ahead. But if you are even, you could've just built a battleship - they do lose out in skirmishes with other units mixed in, but battleships actually do something both before battle (long-range bombardment of enemy navy, which battlecruiser can't do efficiently vs equally-ranged destroyers) and after (killing in-land operations).
So what's my final take? Instead of increasing it's HP (that's what frigates and shields are for), I'd either increase it's range so the gun actually fills its role (note that the only '+' Valiant has is quite not that big of a plus, the DPS advantage is 10% over the 2nd best, which is not a lot) and makes use of it weapon (you maybe don't have to match the 80 range Salem and Exodus, but give it middle ground of 70, between them and Uashavoh). Another solution would be to make it more self-reliant, and have it's sonar, radar and vision ranges increased. Maybe in addition to that, make it's torpedoes slightly have larger range (but keep the poor dmg).
Another solution that's more on the silly side is, give it air-staging capability. Not that it's gonna increase it's solo potential, but it increases it's value and it'll actually give UEF a non-experimental naval-based air-staging facility. Cybran has both the cruiser and the carrier, while Sera and Aeon have the carriers. UEF has Atlantis (which is 3x more expensive than the T3 carriers).
