I'm struck by how similar the points raised in this thread mirror what was given as feedback for ECM when it was introduced. To date, the Devs haven't done a single tweek to ECM, so I wouldn't expect them to change Seismic either without setting a valid argument for hypocracy. Likely, they will add in things like decoys and/or allow Streak SRMs to temporarily blind Siesmic when they hit, though to be honest at least Seismic has a very easy counter to it, unlike ECM, so the degree it needs a counter will be different.
Ultimately, it seems like they are setting up a situation where scout mechs must remain out of close/medium combat ranges to do their jobs (the BAP abilities vrs ECM combined with Seismic sensors) rather than rush into point-blank attack ranges. Might be good as encouragement for proper roles, but I don't know if alot of Light pilots will be happy doing the jobs a Light mech is made to do. They are leaving open the option for the Light pilot to disregard their role and engage as a brawler, but putting obstacles in that will make that a very costly risk. Is this good for the game as a whole? I don't know.
Is the range on Seismic too great? I don't know, since the only thing that would make this worth the 17500 GXP, 6mil Cbill pricetag is if it actually had a benefit on the battlefield. Since the whole point is to see enemy units before they get close enough to make detection pointless (dual AC/20 range+the range needed to avoid), it needs to be far enough away to matter, yet not so far as to allow long-range avoidance of combat. At the same time, a Scout unit using this needs the extra range to be able to do it's job, so having it only detect something inside 250 m with most maps having 300m visibility angles would probably make this unusable as Scout equipment. The range seems about right for this, though I'll reserve judgment till I've got some more battlefield experience to tell.
As for the most powerful item in the game, I think ECM still edges it out in having infinite range abilities (cloaking everything under its protection from being targetted at 750meter and beyond) and not requiring a Module slot (which mechs have far fewer of than crit and tonnage), and among the Module items, the UAV is arguably more powerful as it allows targetting of the detected enemy mech for LRMs (unlike Seismic that only gives indication, not targeting, and can't detect unmoving units).
We'll see how this plays out, but I expect it will end up being like ECM.
Edited by Jakob Knight, 23 May 2013 - 05:48 AM.