I don't see why a shrouded firing pin would be a benefit when using a semi-auto AR-15. The reason Colt created this cutout in the first place was to catch the semi-auto hammer in the event of a disconnector failure. It's easy to test this feature yourself by pulling back on your charging handle, and as you ease it forward, release the hammer by pulling the trigger. This should cause your bolt carrier to "hang up;" that's exactly the way it was designed. If it doesn't, and your disconnector fails, it could result in a slam-fire. This is exactly why your semi-auto hammer has that little notch on the top. It's meant to catch on the firing pin, which it can't do if the bolt carrier covers the firing pin.
To each his own, but I wouldn't want one of these in any of my semi-auto rifles. Field agents know all about this, and I can tell you that before anything else, they will try this test on your rifle. The next step will be testing with "soft" primered ammunition, and possible tampering with the disconnector. Why give them the opportunity for little or no benefit to yourself in the first place? (ATF agents reading this are going to hate me!)
Keep it legal, and have fun!