First of all I am not a fan of running the ETX 9. It is one third of the CCA of the stock battery. You will typically run into problems with extended cranking or big cc, big compression motors with it.
Now, as far as the total loss goes, keep in mind that lead acid batteries, including AGM, are not designed to be rundown and recharged repeatedly. This greatly reduces their life and their performance. In addition as they run down over the course of the day, they lose voltage and thus your ignition, starter, and all other electrical equipment will gradually run on lower voltage and thus be required to consume higher current to do the same amount of work. (W=VA). If you lose volts, you need amps to make it up.
Lithium batteries, on the other hand, are designed to be rundown and recharged multiple times. If you look for the data sheets on the particular cells in your LiFe battery, you will find the cycle life is rated in the thousands. This means that they are well-suited for the constant running down in recharging that we subject into with total loss.
However, the only catch is that they are very sensitive to being over discharged (meaning run down too low), and are subject to irreversible damage if this occurs. This is the reason that most companies do not want to warranty them for total loss, as they fear that they will be run down below the minimum operating voltage, thus causing cell damage to the battery, which is not covered under warranty.
To answer your question about the voltage specifically, the life cells that we use maintain a constant voltage around 13.2 to 13.3 V, from fully charged to almost fully discharged. This means that our electronics see the same 13.2 V for the course of a riding day. The fact that it remains at 13.2 rather than 12.4 to 12.6 like an AGM, means that we will have slightly improved ignition and starter performance due to the higher voltage. This higher voltage also means reduced current to the starter and start relay, meaning easier starting and hopefully longer starter and starter relay life.
Once again the biggest issues/benefits are seen on the bigger CC motors with high compression.
I've been selling battery kits and ignition kits to customers for years with few to no issues. This is because I sell proper chargers, spec the right battery for the application, and do some additional waterproofing on the cells to be sure that they do not get water damage. I run the same stuff in my personal boats, and in all the competition boats that I sponsor and build. I only sell what I use myself and what I truly believe is the best product. However, as previously mentioned, most issues are customer use/care. Battery failures are rare. Impact damage, water intrusion, and improper charging/operation is far more common, and not the batteries fault.
