Bit late to the party, but here none the less...
I've got H7 & H1 HID's in my LC and haven't had problems as yet (touch wood)
They are a bit of a pain to fit, as you have to DIY an earth loom, as OE H1 bulbs use the metal part of the bulb as the -ve return, where as the HID's have 2 leads from the bulb.
Like I said mine have been fine, and have been on there for about 6 months now.
Flash isn't a
problem as you get a natural flash from the HID when they initally start up,
I have been warned about the reduced life time of them, but MYDEPOTS do replacement bulbs for about the same price as top end Halogen blubs anyway, so I figure I'm not lossing out much...will just have to see how the ballasts stand up to the test of time...
I did do a mini How-To for the H1's and there should be pic's of the earth loom that I made for the job somewhere...I'll check my Photobucket for the image if it's still there...
Only thing I would say about your current HIDs not being quite bright enough is that 6400k bulbs are a little too blue for my liking...I'm running 4300k and they are like daylight just on dipped beam...won't even go into what it's like once the H1's are running too