I haven't read the other thread but I have found a solution to heel problems in Inov's that works for me.
Boots sell a felt padding which is very adhesive and can be stuck directly on to the back of the heel. You may struggle if your shoes are already a very tight fit but otherwise, and as in my case, it can turn unwearable heel choppers into excellent fell shoes.
Only a few quid and comprises of a strip which is long enough for a few pairs. Looks like this.
http://www.boots.com/shop/product_de...7317&slmRefer=
It says on the packaging that you should stick it on your skin, but I stick the tape on the heel of the shoe itself. I've done loads of races, mountain marathons etc in them and it's stayed put, just maybe worn slightly and eventually needed replacing.