It is interesting that you focus mainly on LiFe batteries. In my opinion they are the worst value for money out there. Yes they are light but that is about the only good point they have.
In a yacht a good set of AA or AAA NiMh batteries formed into a 4 cell (4.8V) or 5 cell (6.0V) will generally set you back far less and as long as you look after them they will last a good 5 years or more.
I recently had to replace 1 cell in a 5 cell AA pack (that I use primarily in my larger yachts) that was made with cheap HobbyKing NiMh cells way back in September 2012.
Most transmitters (but not all) will take 4 (or sometimes 8) individual AA batteries and 4 x AA NiMh fit this bill also. Yes they only produce 4.8V and not 6.0V but they will still keep your transmitter running for many days of sailing.
Its horses for courses I guess. This guide was prepared by Phil Burgess and is not definitive by any means. As Phil is information central for all things DF, I guess his guide is his opinion on what is best in DF yachts. I personally use Life batteries and like them for their low cost, safety and light weight….. this is particularly important for these yachts competitiveness where every gram counts.