Going to the mat is really not an option when you're 60, . . . got a minor heart condition, . . . at least one bad knee & hip.
Most of the time, yes, . . . my 1911 has some kind of retention strap, but a couple of the rigs I use don't, . . . and I'm just not going to worry about it too much.
Don't really figure on being the winner of any "mat" exercises in the near future, . . . but I do figure on being the winner if it becomes a shootout.
In answer to the question, . . . IMHO, . . . there are some good IWB rigs out there that are safe enough for CCW carry. That is especially for a non LEO. LE work can tend to get a bit "personal" and it would be up to the LEO to make that call, . . . but for general CCW, . . . I have no problem with a good IWB rig or even some of the paddle rigs.
May God bless,
Dwight