I just got a RAT9 as my first gaming mouse and have found the transition very easy,
If you are struggling after five months I'd try and identify the underlying cause,
go back to a normal keyboard and familiarise yourself with the mouse first, get used to pressing a certain button instead of a key on the board or moving the mouse and clicking,
most mice have profiles for browsers as well as games so set your browser profile up and maybe put your keyboard hand behind your back
MAKE yourself use the buttons you have assigned to functions and it won't take long before your brains trained to use that method instead, freeing up your keyboard hand for other things or just making its life easier by having less to do,
I trained my brain for WASD/mouse gaming using Portal and Portal2, very forgiving sandbox games, then moved onto Alice2:Madness returns which has smarter enemies and requires a little faster responses,
Mass effect series and now I'm on Crysis series,
Once you are really comfortable with using the mouse swap over, use a normal mouse and start using the keyboards macro/hotbuttons, same again get used to everything you need/want to,
then when you are happy with that, go full gamer spec on both and your brain should handle it well, if not welcome the new gear because its now used to it,
Some folks take time to adapt, others pick up straight away but keep at it and you should get there relatively painfree
Sidenote, I got my mouse on friday and am now completely comfortable with it, my Kb hand only needs to do wasd and relax
Moto