Given what Paul stated in http://mwomercs.com/...apon-balancing/ , I think he's looking for somnething that starts at 3 Streaks and moves up, so I'd say no penalty for the second, then a sharper ramp for third and beyond.
On the issue of Clan Streaks. I think these may need to be considered carefully. Inner Sphere Streaks weigh in at 1.5 times the basic SRM launcher, Clan Streaks are twice the mass of the Clan SRM launcher of the size. This also means that Streaks for the clans carry more of a penalty compared to Inner Sphere with regards to SRM+Artemis fittings. In the end, Clan Streaks may be penalised a little differently than the IS.
Still, it is another way to look at things. I am not sure that the devs really want something calculated using default pilot skill levels. Sadly, using Battletech skill levels as a calculation factor in balancing would seem to fail in MWO.
Edited by Voidsinger, 26 November 2012 - 06:45 PM.