You are an animal Mike, how do you manage it!? Mine survived a mauling beyond speakable belief at that Crowthorne race, I can't believe you can do anything that horrendous voluntarily in 5 weeks of use!
How are you clarifying worn out Mike? Do they actually stop working? You must be doing something wrong, no offence but I'm sure I ride more than you do, and I know people who live round Soton and the soil's not that much different, you MUST do something to kill them that fast, I've never had to change one!
Get yourself a titanium middle ring and forget all about wear and tear.Done a few muddy dirty rides and it hasn't got a scratch on it and still looks like brand new.An aluminium ring would be suffering by now with loads of scratches and teeth starting to get hooked.
Maybe a daft question, but you have changed your chain regularly/after completely lunching a ring?? 'cos a f*cked chain is a surefire way to chew a ring, and vice versa. I'm sure you ain't daft, but I had to ask!
Mike your not alone, 3 months is the longest I have managed from an LX/XT middle ring :( and I have 3 bikes to share the wear out with. Deore Steel is my answer or CycleDynamics Ti if your flash (which I am not)