Not the biggest fan as most seem to be fitted to cars (mainly Renault 5 turbos) that are running a fart's worth of boost and sound like defective air brakes at best, but my car is running approx 23 psi, so couldn't realy get by without it.

Doesn't sound too bad either for the same reason.
A combination of this, the noise of the turbo, the sound of big fat fuely flames cracking out the tailpipe on the rev limiter and the howling/sucking of an angry/hungry/thirsty CVH at 7000+ RPM makes for a pretty addictive soundtrack.

Also gear changes and pick up are both quite swift, this may be due in part to the valve, but that is only conjecture on my part.

Originaly would have been very bad idea to fit d.v. as standard plumbing meant that operation of the valve sent the metering unit and consequentially the fuel mixture completely doolally, i.e. lean and then rich and so on, resulting in horrible driving experience and eventually damage to engine from a combination of pinking and bore wash (nice).

However, I was informed a number of years ago when my engine was built that some clever fettling had been done to the air plumbing that allowed the use of a valve without causing fueling problems, thus enabling the use of higher boost pressure.

I think in other cases, using a valve needlessly is just stupid; and should only be employed as a last resort as in the case of my engine. But then that's just my humble opinion.
Cheers.