I have been eating very very hot foods for ' quite a long time '...
When you start, you do notice intestinal excitement to put it mildly, but you become accustomed to chilli after a while, indeed you may find that you become a touch constipated if you go chilli-free.
I am on Dorset Naga chillies now, claimed to be the hottest in the world by some margin.
http://www.dorsetnaga.com/
http://www.timesonline.co.uk/tol/news/uk/artic le700700.ece
I add a whole one chopped to every curry I cook now, and they give it a real zing.
I know exactly the reasons you want to go hotter and hotter, it is like an addiction, but you get an amazing endorphin rush from chilli.
In my cupboard I have at least 30 different types of chilli sauce. The only meal to which I do not add very hot chilli is bolognaise. For a real treat try hot tinned kippers smothered in Encona and loads of white pepper.
Is it bad for you ? Well I am still thriving.
Hope this helps.