Looking at that Shorai Li-Ion battery in the NSX, I searched it quick and I don't see any charge protection built in to that battery. Run that one low and its a goner. Would be good to throw in a race car for track day but not on a car you drive often. You'd need to use their charger or disconnect it when not in use and keep an eye on it.
I looked at the Braille batteries but they seem way overpriced. Me and pacecarta are using the Deka ETX30L. Its the same one as the Braille battery for 1/3 of the price. At 400 cca its got enough reserve to work really well. I had the PC680 but at only 170 cca it doesn't have much juice and didn't work for me.
For a good Li-ion battery with protection, look at the Lithium Pros ones. The smaller ones are limited to 100A available from the alternator, so a 200A alternator may not be good. I considered getting one, but it wasn't worth $1,000+ dollars to save 14bs over the Deka.
One thing we learned with the smaller batteries is that they do drop voltage on startup, especially if they aren't fully charged. The XFI I have is very sensitive to this. Pacecarta finally figured out to hotwire the ignition lead to XFI (not the battery lead) for both our cars and this kicked up the voltage enough where there are no more starting issues. A really good thing about Li ion batteries though is that voltage output remains very steady until the battery is discharged. Startups are supposed to be great and they really shine for race cars with no alternator.
