Velocitek devices are OK to use in the A-Class and other classes unless the class specifies differently.

The A-Class Association clarified this last year and published on their website. The text is:

"Dear Piet,
As far as I am aware there is no general Racing Rules of Sailing prohibition of electronic equipment including GPS.
If a class association wishes to control the permitted or prohibited equipment then these should be specified in the class rules.
Regards
Simon Forbes"

The linky is:

http://www.a-cat.org/id113.htm

I think these devices are great and shouldn't be limited.