Having trained with John some, I can reiterate what Mike said, Ask him.
On the grip adapters issue I have seen on more than one occasion a grip adapter for a magazine ( like the one that makes the XD compact grip to a full size grip) slide down the mag and make it unusable!! the bad part was the other two mags the lady was running did the same thing at the same time, thus "taking her gun out of the fight" not to mention the loss of training time for her wile the instructors helping John had to "fix" her mags.
John will not disallow any gun just because he doe's not like it, only if he has seen a safety reason for something in the past.
And one thing about John he uses different "stuff" all the time, he really try's to keep up with what is on the market.
On the grip adapters issue I have seen on more than one occasion a grip adapter for a magazine ( like the one that makes the XD compact grip to a full size grip) slide down the mag and make it unusable!! the bad part was the other two mags the lady was running did the same thing at the same time, thus "taking her gun out of the fight" not to mention the loss of training time for her wile the instructors helping John had to "fix" her mags.
John will not disallow any gun just because he doe's not like it, only if he has seen a safety reason for something in the past.
And one thing about John he uses different "stuff" all the time, he really try's to keep up with what is on the market.