I have heard this argument/discussion a few times, and for carry I would not consider a rail gun, it just doesnt make sense... Although for home defense I would not have a gun without it... As far as the argument of "it gives away your position", the lit doesnt have to be lit, lol thats why god invented switches and buttons...
This post may get long, I apologise in advance for that...
When I built my hd gun I went through a few different scenarios and I always kept a semi auto 12ga loaded with 00, under the bed... BUT then I went to a self defense class where the navy seal/personal security professional ran us through a mock home and ran us through some situations with different weapons, and also had us on both sides of the confrontation.
We tried SBR ar15's, bullpup platformed rifles, shotguns, a saw'd off side by side, a few pistols, ect.. This was an 8 hour class with 12 students and 2 teachers, so very hands on...
Time after time the full size pistol with a rail mounted strobe light, laser pointer and night sights, worked... We went from pulling it out of nightstands, safes, out from the mattress, every scenario you could think of!!! He had us run on a folding treadmill until our heart rates were jacked then lay down, and jump up to arm our self, I can tell you first hand doing it with your chest pounding is WAY more difficult that doing it relaxed...
The lesson of the class was find a pistol you are comfortable with that you can manipulate at 3am with your heart rate over 120bpm, know how to use it, right down to the light, with the gun loaded he showed us how to use the light and our non primary hand to just glow enough to see our way, how to acquire the target in the dark, how to walk softly, when to activate the strobe or laser, ect ect ect..
The class was $190 ea. and I took it because it was a day at the range that I could tell my wife was for her, she learned a lot too, and it was just as fun as educational...
I chose the 1911 platform since I am most comfortable with it, I can shoot them in my sleep, I also chose the 400 corbon round because in another class I seen what that round properly loaded does to flesh {impressive, but there are some trashy ones out there too, you need the right load in 400 corbon and it is a destroyer}. I started with a DW rail gun, had my smith install the 400 corbon kit, do some polishing, install a new trigger, some trigger work, different sights, ect. I used the streamlight tlr2 that has the invisible laser {you can only see with night vision goggles], and a set of crimson trace master grips, I spent thousands on the gun but it works perfectly..
I have shot it down range, IT ALWAYS goes bang, I have practiced with it and the system and plan is all there.. I also was taught to have a plan and let everyone in the house what to do in case of an intruder, something else useful that I learned at that class was not all home invasions happen while you are sleeping, so carrying a weapon while home during the day is a good idea, which I never do, but I do have my ccw accessible whenever I am home...
Again sorry for the long post, and I know some guys will say "what a 1911, I would never trust my life to them", well I own $20,000 worth of 1911's and I shoot 200 rounds of 45acp a week and my 1911's go bang everytime that trigger slides, my 1911s shoot the target where I point them, and in 10 years they will still be worth something, some of these new guns are worthless a year after you buy them... {not that resale value should sway your purchase of a defense weapon, but with me it does, I could buy a nice 3 bedroom house with what my collection cost me...}
Heres some of my 1911's, the hd gun is the one with the light attached and master grips, my les baer target gun is in this pick, wilson carry, ed brown special forces, ect...