If you mean the halogen filament bulbs with a bit of xenon in them, I wouldn't worry. It is just marketing.
You seem to lose a lot of light with any halogen bulb that tries to be whiter/hid effect (the "blue" types). The bluer (higher colour temp) bulbs appear to be much worse in the rain than the yellower (lower colour temp) standard halogen items.
I moved to the Halogen Philips Vision 50%+ and they were better than stock GE/Tesla bulbs. I changed the dips in four cars and found the least benefit in the 166. This was explained when I got the lights set again recently (were done by a dealer before). They were set ridiculously low! Why on earth are Alfa lights set so low?
If you look at
http://www.danielsternlighting.com/t...ulb_types.html it is interesting to see that the standard H1 bulb has a slightly higher lumen rating than the stock H7.
I like the idea of a HID upgrade, but my (brief) research suggests that you should at least replace the whole headlamp unit. These seem to be available for the 156. You still have no auto levelling or headlamp washers though...