Anyone on here familiar with the GSL GT-556 can?

I'm looking to pick up an LMT R20 Estonia Reference Rifle for the lady, and it comes standard with a pinned muzzle device for this suppressor. I'm familiar with the Surefire SOCOM and Dead Air Sandman series of Suppressors for AR platform guns. The GSL weight and dB reduction look nice compared to my existing cans.

My questions about the GSL are:

-The mounting system is a bilock design instead of a taper mount - How is POI shift between suppressed and unsuppressed?
-Is the GSL a pretty "gassy" suppressor? In the past I've found some of the "quieter" cans to have more back pressure due to the baffle design which can lead to more gas in the face, accelerated parts wear/breakage, and the occasional malfunction due to bolt velocity and such from the additional backpressure.

I don't have a GT-556 but I do have a Gemtech G5t which seems almost identical in the specs including the bi-lock mounting and I can tell you that it's gassy as f**k.
I love the mounting system and the weight and it's very durable but I still get bad gas in my face every time I use it, even with a gasbuster charging handle and a Gemtech suppressed bolt carrier.  
I'm thinking about asking Ecco if the baffles can be modified to reduce the gas blowback because I'm really tired of the gas bukake to the face.

Have on an LMT rifle.  Estonia piston gun.  works great.  Love the mount.  The fact that reservists are training with this rifle and suppressor combination in a little country mostly surrounded by Russian makes it even more cool to have the rifle and the correct can.  At 14+ inches, there is no gas blow back.  Well, maybe the piston helps a little.

I have an old Gemtech G5. Not sure how much the GSL design has changed, if at all.
POI shift is ~1" down at 100 yds with the can (depending on the barrel).
Bi-lock mount gets dirty enough after a couple of mags that you had better take it off while it's warm or it's going to be a PITA to remove later.
I run it mostly on a 10.5" DI AR. Adjustable bolt carrier and Raptor SD charging handle definitely help with the gas in face.

Im somewhat vested in gemtech mounts for a lot of older obscure rifles so I do have some older gemtech cans on hand, but can anyone tell me when gemtech and gsl seem to be much more pricier than their competitors?