Worth having, but expensive for what is neither more nor less than a stock distributor fitted with a Britpart ignition module and one-piece rotor arm.
Unless your distributor is particularly worn, I'd recommend fitting the module to that since the "modification" is simply the snapping off of the post that allows the sliding contact to shuffle back and forth on 43 and 45D distributors with self-cleaning contacts. On the ones with the other type of contacts, the Britpart kit fits straight in without any trouble.
Buy one
HERE for a shade under £13, which is quite a saving over having someone fit it to an unknown quantity distributor that might not even come with the right weights and vac. unit for your car.
The chip inside the distributor is the same one that S***n B*C uses, this I know as I once tested a bunch of different systems for members of another forum I use.