The RS Aero price list lists a Tack Tick Mount for £56 which is, I assume, the item pictured in the rigging guide. As its being sold by RS on their official price list I can't see them excluding the use of a tack tick compass when the rules are published.
There has been debate on other sailing forums about the legality of tack tick equipment. The basic tack tick unit is simply a digital compass and gives no greater advantage than using a conventional compass. This is very different from some of the tack tick equipment for yachts which integrates a wind direction gauge with a compass to spot wind shifts. This kind of equipment is against most dinghy rules.
I was told this weekend that the class rules are with ISAF, so are iminent, but in practice, RS are providing a TackTik bracket, so we can assume that electronic compasses will be permitted.