First I will compare the same 5 skull mission, a Battle in a Lowlands biome, using same pilots (with "equivalent" builds) and same 'Mechs. Then expand on some abilities.
>Normal version:
- pilot 1 (AS7-D-HT): Bulwark, Multitarget and Breaching Shot.
- pilot 2 (HGN-732B): Evasion, Multitarget and Breaching Shot.
- pilot 3 (HGN-733): Evasion, Multitarget and Breaching Shot.
- pilot 4 (BLR-1G): Sensor Lock, Evasion and Master Tactician.
All pilots maxed (skills at 10/10/10/10), and most 'Mechs customised with more armour.
OpFor: two demolishers, VTR-9B and KingCrab.
Reinforcements: Zeus, two BNC-3E and AWS-8T. Arrived after 2-3 rounds of combat, flanking my lance from around my 4.
Result: no injuries nor structural damage taken. Used my Evasion pilots to move around flanking, Sensor lock to reveal enemies before having LoS. The Bulwark pilot providing extra fire from a visible position (trying to draw some enemy fire). Happy mission as usual.
>Beta version:
- pilot 1 (AS7-D-HT): Fortify, Multitarget and Breaching Shot.
- pilot 2 (HGN-732B): Sure Footing, Multitarget and Breaching Shot.
- pilot 3 (HGN-733): Sure Footing, Multitarget and Breaching Shot.
- pilot 4 (BLR-1G): Sensor Lock, Sure Footing and Master Tactician.
As before, all pilots maxed (skills at 10/10/10/10), and most 'Mechs customised with more armour.
OpFor: two demolishers, VTR-9B and HGN-733.
Reinforcements: HGN-733P, two BNC-3M and AWS-8T. Also arrived after 2-3 rounds of combat, from the same position, so I was prepared and no flanking happened.
Result: AS7-D-HT lost RA and RT, with the pilot taking 1 injury. HGN-733P structural damage at RL and LT. BLR-1G structural damage at RA. Obviously, the difference in the result is not only because of the pilot skills, there is RNG, slightly different OpFor and, mainly, I wasn't familiar with the new skills. Sensor lock works almost the same, but with Sure Footing I traded more stability (which barely ever is a problem) but less evasion (especially when jumping to flank or backstab the enemies). Fortify it's a complete new mechanic, so I didn't use it properly I'm afraid, hence the beating on the Atlas II.
So, my final thoughts on each reworked skill/ability:
- Sensor Lock: I disagree with the "one-trick pony", it was useful before, especially for dealing with several sniper turrets, soften incoming enemies before reaching LoS and make quick 'Mechs easier to hit. That's why I always had 1 or 2 pilots with Sensor Lock in my lance during the campaign. Now, with the impairing debuff, it's even better (but nothing overpowered), and I will keep using it.
- Bulwark/Fortify: I need more practice with this one, probably using the Vigilance synergy as others have mentioned. It's true that makes the combat more difficult, and it's not a must for tanking, but I'm not sure if it's makes the combat more dynamic, as it's an ability that only does something if your 'Mech does nothing, apart from moving. Although it definitely helps with balancing with other skills. After this change I will probably use it less often.
- Coolant Vent/Juggernaut: this one I haven't tried, but it's a skill that, as already mentioned, I won't be interested in using. Part of the charm of the battles is to manage your heat. Trading an injury for zero heat generated is not worth for me, and until you can have the MedBay fully upgraded, an injury is quite a lot of time without being able to use a pilot (and time is money). It's true that Juggernaut becomes quite useless by the end of the campaign, when almost every battle is with heavy and assault 'Mechs. I was only picking Juggernaut for the fun and interesting initiative warfare at the beginning/mid-campaign and for "role-playing" purposes (a character that solves the problems punching his way out of them), but I was always wary of how much it would help in the end.
* If I may make a suggestion (although I'm quite sure you already considered and I'm unaware of the reasons to discard it), if you're worried about Juggernaut being not as good idea and also about the knockdown meta, then why not making Juggernaut the same as before (moving one initiative down) and dealing twice (or even x3 times) more stability damage than normal melee attacks? ("Juggernauts are experienced pilots who knows how to take advantage of the weight of their 'Mechs, dealing staggering damage with its terrible force").
- Sure Footing: what I said in the short version, it has some good things and some that I don't like (I won't say bad things, simply not fitting my tactics).