Thanks 2100, I new I could count on you for a well thought out detailed synopsis. I did Google for automotive stock HID replacements rated above 100W and came up with nothing. Through my involvement with deep scuba diving, marine and aircraft certified electronics, Im not about to try to dremel through hardened acrylic or epoxy potting compounds to squeeze a few extra lumens from a high powered ballast. On the flip side, heat sinking is easily accomplished in most cases by anyone with access to aluminum sheet, snips or a jig saw & belt sander.
The coleman host provides a large flat back side to mount the ballast externally where it can exchange heat with ambient air. I want to keep it reliable while being able to run for several hours continuously if necessary... just as it should if mounted in an automotive light housing (which the item you linked to is supposedly designed for). Another interesting thing about the coleman host is that it contains a metallic helacoil in the plastic housing to accommodate threading into a standard camera tripod. Oh the possibilities! 
I didnt realize that there is a difference in arc lengths for automotive related HID gear. Thanks for that info. I'll go with the big fat beam every time, although I suspect a 35W 3mm arc will be far out gunned in range and width than a 100W with 5mm arc. There are dozens of 35W versus 55W HID comparisons on youtube. The 55's kick some serious ass over the 35's. I think I'll avoid pushing 100W through the 35W bulbs that you mentioned for now. I read that the standard DS family of bulbs can handle about 90W before possible catastrophic failure of the xenon envelope (and what a cute small explosion it would probably be). Hah!
The AN-VSS3A's success was completely attributable to the housing and advanced variable geometry warping parabolic reflector design. The engineers went to extraordinary lengths to maximize the efficiency of every available lumen, and while in any reflector configuration. I still havent seen anything like it in any lighting device to this date. At only 14" in reflector diameter, it provided more functionality and range than its much larger and heavier AN-VSS1 2.2kW predecessor.
As far as triple XML setups are concerned, my hydra triple XML mag looked rather anemic when operated at 2.5W as compared to 3W (per emitter). Yeah... the difference was - as they say, "like night and day". Thats why I have absolutely no desire to purchase the chinese triple XML's. They are way underpowered in my opinion, although they may be adequate for close to mid range. But if you've never seen 3 XML's driven to capacity, you probably wouldnt know what you were missing. Yeah, i know you own a TK70... so that doesnt count. 
This is all great discussion and I'll go ahead and purchase the 100W HID setup that you recommended. Thanks for all your advice!
CD5320 - What host are you using for your HID searchlight? Can you give us some details? The coiled power wires on the coleman appear to be 14ga and more than adequate to deliver the proper current. The weakness will probably be at the contact point where the positive plunger pin on the lighter plug contacts the lighter socket, or in the auto wiring itself. I have a small high powered gel cell aircraft starter battery (read: extremely expensive) that I plan on carrying in a small back pack to power this light when its not plugged into a vehicle. Battery weight is just over 15 lbs and delivers 24 reserve capacity minutes.
What is reserve capacity?
Reserve Capacity, (RC) is a battery industry rating, defining a battery's ability to power a vehicle with an inoperative alternator or fan belt. The rating is the number of minutes a battery at 80 degrees F can be discharged at 25 amps and maintain a voltage of 10.5 volts for a 12 volt battery. The higher the reserve rating, the longer your vehicle can operate should your alternator or fan belt fail.
Although hard to calculate exact figures - because specs arent available for the HID power consumption and discharge graphs at various amperage draws for the battery, I should probably get at least 1.25 hrs of run time if not closer to 1.75 hrs. If Im not satisfied, I'll seek the serviced of Reverend Jim and build a massive 18650 pack to power it.