I have to agree with Dave & Jinx
What needs to be considered IMO
Is what kind of bike can you get for 10K
Will it be as good as your current bike with that 10K spent on it
If the answer is no, then you have your answer
But if the bike you have now isn't "in your soul"
If it's just "a bike" that wont be missed or mourned
Then no amount of money spent on it will help
But if it's part of the "family" then it makes "economic" sense at least, to upgrade it
If you fancy the idea of a "new bike" then go ahead & spend 18K