Yup as Aegis pointed out I fitted a HID kit to my Gen 1 about 3 or 4 years ago. I bought a single kit from fleabay for about 40 squid (chinese supplier). and it was a straight forward fit (fitted to the right hand lens as you're sat on the bike). Ballast tucked under the right fairing infill & a straight fit into the bulb holder. I just kept the standard bulb in the left lens. My intention was to eventually do the left lense with a HID, but in all honesty, it's just not necessary as the other one is so bloody good.
My bike is ridden all year round all weather & the 40 quid kit has given me no problems what-so-ever; still on the original bulb.
It's just been through it's 3rd MOT with the kit fitted with no problems. I've been on 3 police lead instruction days & have had the bike looked over by, "traffic" after being stopped a couple of times...never has the HID been commented on negatively.
as for blinding oncoming traffic, i feel that If it's fitted well and the aim is correct with the riders (and more) weight on the bike, it shouldn't be an issue. but I know folk will contest that. I've not had any of the folks putting their lights on to high beam to tell me i'm blinding them.
Is it necessary in towns and city's? prolly not, but if you live in or commute through the countryside or enjoy a right good ride in the countryside in the dark
then imho, it's well worth doing.