I haven't done this, and I'd like to tell you why.
That mag-well attachment is about as necessary as teats on a bull.
• To begin with, it sticks out past the grip, so it makes your gun somewhat less concealable. After all, it's the grip, not the barrel, that's the hard part to conceal.
• For about the same price, you could have a decent gunsmith bevel the inside surfaces of the gun's original magazine-well area. Or you could do it yourself with a file, for free. That would accomplish everything your new accessory will do.
• From now on, you're going to need magazines with thick bottom pads. Otherwise, you won't be able to fully seat them past the opening of the mag-well funnel.
No, I don't think it's a good idea, or a useful accessory on a concealed weapon. But, as they say, your mileage may vary.