Damn, I was hoping to be the first and spring a surprise. But musn't be dog-in-manger so here's what I found out so far even though I haven't done it yet.
1) Mr F reckons that there should be no reason in theory why it can't be done. It's a modern V6 with ECU so "should" be OK. (as long as it's healthy and as long as it doesn't have some appallingly setup aftermarket bodge).
2) My local mobile car sparks came round in an LPG'ed Nissan Stagea and after curing a few dodgy bits, says it's now fine.
3) I emailed / filled in on-line forms to several places but only ever had two replies: one from a garage in NW London who said £999+VAT for Lovato equipment and one from one in Surrey at £1,599+VAT for BRC Multipoint.
4) I'm a bit cynical about such a price difference but then again you get what you pay for. Just haven't got into my comfort zone with either yet. Still more research to do.
5) A few year's back, a colleague of mine had it done to his Cherokee Jeep and he said yes, it cut his performance/mpg by maybe 10% but it cut his fuel cost in half so he didn't give a rats' whatsit.
Be interested if anyone has other advice, too.