It's looks a good deal for you. There was probably some element of discretion regarding the bonus, now you are 'guaranteed' the 10,000 as its included in your basic.
However, if you have a deal which might give you 10,000+ in a bonus this year (and you feel confident of exceededing 10,000) then its not so good.
You also have to look forward to future bonus earnings and how sure you feel about achieving those.
Better to be on 40K. Salary is better than bonus, if the amount is the same.
If you looking for morgage, based on multipe of base salary.
If you get layed off, redundo money calculated from base salary.
Also might have some effect on pension contributions, but not sure on that one.