More than likely, this.
Do you mean this area?
I prefer the Magpul overmolded grips but I went with the Magpul MIAD grip, same as what MI uses on theirs. This grip allows you to swap out front and back straps, the one without the beavertail being used by default. This grip config felt a little thin to me and I also found the 3rd knuckle on my index finger was taking a beating from the chassis area just below the QD sling mount hole. I had some time off over the holidays and was a big bored, so I took the thickest beavertail back strap from the MIAD kit and attacked it with a coping saw and my Dremel tool to shape it to the chassis and receiver extension. About an hour later I had what you see in the photo, coupled with a grip that is more comfortable, fits my hand better and a happier knuckle to boot.
Yes and yes. Another reason I went for the Spitfire 1x, plus the reticle is actually etched so if the battery dies or you don’t want the illumination, you still have something to use. Not sure if they make this one anymore, feel like it’s been replaced with an AR version (same reticle and functionality, different mounting and shape) that doesn’t work well for me. That said there are still some for sale out there.