Use spaces not commas to group your thousands in English too?

Are you switching your separators in 2,000 and 1,121,121 now 2 000 and 1 121 121? French went that way long ago. But in 2003 the BIMP made it official.   Now I'm stuck between my Gregg Style Guide and th BIMP.

I like my comma separator but metric standards agreed to the following SI (Système International) presentation for numbers:

declares that the symbol for the decimal marker shall be either the point on the line or the comma on the line,
reaffirms that "Numbers may be divided in groups of three in order to facilitate reading; neither dots nor commas are ever inserted in the spaces between groups", as stated in Resolution 7 of the 9th CGPM, 1948. 

BIPM - Resolution 10 of the 22nd CGPM

So, group with blanks and the comma or period for decimals. I suggest using blank non-breaking spaces of course, in MS-Word use CTRL+SHIFT+SPACE.

The use of commas is restricted in lists as well, lists using  "comma separated variable" is being  replaced by "semicolon separated variables" or tab delimited variables. Source: Comma-separated_values

Steve