«we shoudl allow comma - just think not at the same time allow» Then I could tweak your regex do to that. Would such a patch be okay (I fear the "ultimate patch" will take a lot of time to be ready)

«it might depend on the browser or if javascript is involved before it's send?» No JS involved AFAIK, but yes it depends of the browser. Do you remember which caused problems to check if that's still valid.

«it's all over messy. I think the more simple the solution, the better» +1
That's why I'm hoping to split the issue in two to fix the truncations and x100 case before the rest (1.000,5)