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