Thanks for everyone's input! This forum is an awesome source of information.
I just wanted to make sure that I wasn't overlooking something that I needed to consider. If you go back six years or so in the posts, its amazing to see how much aviation technology in general has changed in that amount of time. I am sure that the Lithium type batteries will be in the mainstream of aviation at some point in the near future.
So here is my thought process.
1) The PC680 is an older but proven technology and appears to be in the vast majority of RV's. Lithium is still a newer technology and there may be more revisions before the technology in aviation is considered mature.
2) This is my first home built project (hopefully not the last) and there is more that I don't know than what I do know. When considering Lithium batteries, I would like more confidence in knowing how things are affected, like safety, weight & balance, and electrical/mechanical modifications. This spells more delays in completing my project.
3) The Lithium batteries have a "cool" factor but appear to be at least double the cost of the PC680 and the lightweight of Lithium batteries seems to be the biggest selling point. If I can save about 10lbs of weight with a Lithium battery, it would be more advantageous to me to lose at least that much from my waist line.

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4) Saving space on the firewall would be nice but.........the PC680 has a home under many cowlings.
5) I live in a very warm climate, so my cold starts would be more of a cool start for the majority of my friends up North. The PC680 seems to have enough cranking Amps for the majority of my starts.
6) I'm using Dynon backup batteries on my SkyView displays (mainly to prevent them from rebooting during engine starts) which will buy an hours worth of instruments in the case of an electrical failure. My handheld radio should cover the Coms. At that, I'd still have to lose my main battery and alternator/regulator.
7) After all of that I ask myself, "What does a Lithium battery buy me for double the cost?" All that I can come up with is about 10lbs. While important, I've already removed a lot of weight in prop governors/CS Props and going with the Catto.
Decision: PC680 for now and I can always modify later as I get more familiar with my airplane. Thanks everyone!