This comes down to a different problem. Light mechs are supposed to be scared of guided missiles, and a Kintaro or any other fast mech boating SSRMs to hunt lights is supposed to be effective. Yes, in a 1 v 1 with a light mech vs a kintaro Streak boat? Your light is in trouble. Add ecm? Negates that a bit, tag, negates your negation, etc.
The problem isn't that SSRMs are broken, its that you are forcing a fighting style that meets its flaw. A light mech on its own, rushing enemy lines, without support, is vulnerable. MORESO with a speedy streaker to hunt you down. SSRMs I propose are not broken, I believe people's expectations within a light mech are.
If you are running all over the map, alone, without support, and you find a mech that can kick your butt? you are in trouble. Bring that kintaro back into your friends for them to chew him up so you can continue.
SSRM's are a part of the game, and their guided death is also a part of it. This is all part of the metagame. I cannot support the idea of 'breaking' SSRMs so light mechs have an easier time running around alone without support. You cannot have a discussion about changing SSRM's without also including why this change should also be for LRM's.
If you can give me a proper example of why SSRM's are broken, other than they kill lights, then I'd be happy to discuss and review that.

My 2 cents.