The H/W is definitely the way to go. You'll virtually eliminate ALL the typical pitfalls of the leak-prone original equipment and have a "set-and-forget" carb.
As for carb heat.....as Tim mentioned....it IS necessary regardless of where you're oriented. The water-heat route is full of potential leaks which will leave you stranded while the exhaust heat, which requires no "valving" functions efficiently because of the firing order of the engine.
I would suggest you use Langfon's heat plate as he has located the openings for the fittings. I found the 3/8" compression fittings gave me plenty of volume and the copper line is easy to bend in your hands. I've got pictures of the setup in my webshots albums and have over 13K miles on the exhaust heat setup. Hope this helps you make your decision.
Dave
