I have been shooting G5 Montec since they hit the market. As a mechanical engineer for over 40 years now, I had finally seen a design that looked to me as the perfect head.
One piece, cut on contact, structurally sound and designed to be sharpened easily.
The one improvement they have made is making them out of carbon steel as they are much easier to sharpen when compared to the stainless.
Few years back I had a party of eight bow hunters in RSA. The first morning there we were all shooting with the PH's. There was as many broadheads as hunters, and even a few more.
By the end of the ten day hunt ALL were shooting Montecs.Several had not so good experiences with the heads they had brought with them.
Good thing I had a few extra heads and that the outfitter and PH we hunted with had asked me to bring him 2 dozen Montecs.
As a note, all of the PH's preferred their hunters use the Montecs.
One day I shot three impala and a warthog with the same head and without re-sharpening it.

I have not tried the g5. My first trip to South Africa was bowhunting and I spent alot of time shooting different broadheads. Wanted to go fixed nlade for sure, still domt like mechanicals. I settled on steelforce without the cutter blade. Been very good and fly as true as a field point. I have heard alot of great things regarding the G5's