When ya choose the HID in both high and low beam, you actually only have one lighting element. The switch between high and low is a function of moving the lighting element up or down so it reflects off the reflector at different angles. If the light quits, you have no light at all.
With that, the up side of HID is a longer lasting light many times over the filament type bulb.
I think you will find that the main component of the HID system is the ballast and I would be inclined to think that most vendors of the HID system us the same maker for the ballast.
The lighting element itself is a chemical function rather than a filament. That is what gives it the extended life and lower power draw.
I have noted that when starting my bike with the HID on, low beam, the starter turns over slower. That is because the start up of the HID draws more power than a filament. Once it's up to full brightness, the power draw drops off to less than a filament bulb. I have found if I switch over to high beam, filament, the starter turns over just fine.
One other note about HID. If your running along at night with high beam on, filament then switch over to the HID, low beam, you will have about 3 -4 seconds of nearly no headlight at all as the chemical is warming up. Now if you have the HID on for a while then switch over to high beam for a moment then back to HID, it will be full luminance right away. It's just a matter of warming up. It's alarming at first, but just as riding a Road Glide for the first time, ya get used to it.
I bought my HID setup for my Road Glide on line last year for about $140 something.

 

Thanks for the info Eastern, so you run low HID with halogen hi beam?

 

I'm running a 35W, 5000K kit from DDM tunning and it's a huge improvement over stock. They also include a relay harness so you can run it directly off the battery and it will be switched on by the OEM headlight plug. the only thing is that the harness they send you is designed for a car (or a road glide I suppose) and has 2 plugs. I am **** and didn't want extra sockets, so I modified the harness to have only one plug.

Best part is that the kit cost under $50, and I've been running DDM HID kit in the fogs in my car for about a year and a half with no failure, so I'm pretty confident it will all work out well.

 

I swear by my HID conversions....I fist converted my 06 softail to HID low with a halogen hi and I think 6k or 8k color. The problem I had with the halogen high is the little halogen is ion the wrong position and would basically light up the right side of the road as it was off the the left and not on the bottom portion of the bulb. I just switched it out for a low/hi HID and love it. I also converted my 03 roadglide to dual hi/low 55 watt HID.....wow. I use euroefx.com for all my HID needs...reasonable and great customer service....as a matter of fact I don't think I have had a better customer service experience in my life...they are simply great...all my ballasts are the full size ones and I have no problem with them working and there is always room to stash them.

 

I run motorcycle metals HID kits , expensive but work great

 

I never need my high beam anymore. Only use it to fire the garage door opener.
HID is the way to go! Still waiting for a side by side with the new LEDs. Don't think they're anywhere close to the output of the HID.
The Bi-Xenon bulbs (moving bulb for hi-lo beam) I feel is a bit "new" on the market for use on bikes. Lottsa vibration going on there. I had them on my truck before switching to projectors and they worked great. Just think the jury is still out on longevity.

 

What's better the HID or the LED?

 

IMO...HIDs.
LEDs aren't there yet. Plus they're ugly..

 

Sssssssssssssss

 

yes the bulbs do move in & out. i have a set on my SUPERDUTY, it works ok but you really dont need high beam with the HIDs. i mainly got that option if i get flashed but i adjusted them & dont get flashed.