As a returning player that loves playing commando right now, please reconsider this change.
Many players have invested considerable time and in-game resources to get the Concentrated Fire armor set. The changes to this set on the PTR go beyond a simple adjustment; the 4 piece bonus is completely removed. This will cause the need for many commando players to reaugment this entire armor set, at substantial cost of credits and time. Many will be turned off by such a large nerf and may just walk away.
I don't pretend to know what you are attempting to balance with these changes. However, having played MMOs for years, I do know that there are always multiple ways to address class balance. Maybe just lower the crit chance for the 4 piece? Adjust the damage or heals on specific abilities? You have options. But please, don't remove the core bonus for an entire armor set. I put in a lot of time to get this set, it really stinks to see it nerfed so hard.
There are a few other posts in this thread have some good ideas for fixes, please check them out.