The HISSs could use some buffs, and changes overall to fit the mechanics we now have ingame.
To start with the HISS, I feel as its alpha should be increased to 390, and be given access to the double barrel mechanic. This would give it something unique and also update its old WWII alpha to a more CW standard. With the changes, the reload should be adjusted to be more balanced.
-- HISS
-- 90mm Twin Cannons
-- Fire Mode: Single Fire -> Double Barrel Mechanic
-- Alpha: 240 -> 390
For the Arctic HISS, when it got the MWS update, its ATGM reload was nerfed by 58% (went from 35s-55s), it has much worse accuracy than the standard HISS, much worse handling, and its ATGMs have been throughly been power crept. To begin to address this, I feel as its reload ATGM reload should either be reverted, or reduced to be sub 42s, the alpha on the 90mm should be increased to 390, to simulate it having a double barrel mechanic it should have a 2 shout autoloader, the 90mm accuracy should be reduced to be around the .31 range, and the hull rotation be increased to around the 44 degrees.
-- Arctic HISS
-- Twin 90mm Canons
-- Alpha: 240 -> 390
-- Fire Mode: Single Shot -> Autoloader
-- Clip Size: 1 -> 2
-- Intra-Clip: 1.13s
-- Reload: 4.4s -> 13.2s
-- DPM: 3274 -> 3265
-- RoF: 13.64 -> 8.37
-- Accuracy: .35 -> .31
-- Aim Time: 2.3s -> 2s
-- Cobra ATGM Launcher
-- Reload: 55s -> 40s
-- DPM: 3102 -> 3428
-- RoF: 2.82 -> 3.42
-- Tracks
-- Hull Rotation Speed: 38 -> 40