I have had 3 root canals and I know what you mean by a sensation. When I press on my gums above where I had the last one I can still feel something. Not pain really, but its hard to describe.
Technically if they removed all of the root you should have no problems. My sister had one done and they did not remove it all and she ended up with a lot of pain and an abscess and went thru a whole ordeal.
I've never had that happen, however a dead tooth will become weak and brittle over the years.
My oldest root canal was done 10-15 yrs ago and the tooth is now darker and yellower than the rest of my teeth and it is full of cracks. The back fell out of it once and I just got it filled, but I will need to get a metal post inserted and a veneer eventually. I've only put this off since it costs a lot (about $1000 cnd) and my insurance might not cover it.
Other than that, you shouldnt have any problems that I know of. I hope this helped