I have used Simon before he was a great bloke and mapped at a good price.
I have also used Jason and B+W Chiptune since and Jason literally writes the map in front of your eyes and will go back and rewrite if needed. Simon just uploaded a prewritten map. Tbh i dont think it makes much difference and Simon is easier on the wallet. If you're after a more indepth map with good after care and a knowledgable chit chat then Jasons your man. Also Jason has a rolling road so nice to have pre and post dynos too