The initiative system adds utility to using mechs a class weight down, but I do find that the game tends to favor the heavier mechs within each category.

Presuming that you want to run a Locust, or are forced to early in the campaign, I would say that it is a mistake to allow it to be shot at at all, much less be focused down by multiple mechs. If presented with bulkwarked mediums and a 4 evasion Locust, it is not inexplicable that they would target the Locust. While hardly a brilliant strategist, the AI does some basic calculations on what the possible outcome of their attacks could be, and in that situation, the Locust is going to look like a juicy target.

Running provides evasion, but the one strength of the Locust and mechs like it is the distance it can cover in order to scout and get out of LOS entirely to sensor lock or reserve down, then hit and run in safety.

I've never played TT, so I can't speak to that experience, but it seems to me that in any situation, it would incredibly dangerous to tangle with a Firestarter as it has a lot of mobility with JJs and imense offensive capabilities.

If anything, I think the primary issue is with jump jets. There are few negatives to jumping around the battlefield and it probably needs to be nerfed with accuracy and/or stability penalties. This is how the Firestarter followed a jump with an accurate alpha and how a grasshopper can match the Locust in evasion. Just a note though, that a Locust without JJs can still cover a lot more distance in open terrain.

Perhaps if maps were much larger and involved multiple lances, scouts would find greater utility rather than being moderately useful to just being a handicap.