As Scott says, the lithium profile holds many potential advantages, particularly for longer term cruisers. The one disadvantage in my mind is that they are too lightweight for the Amel 54 and maybe SM too??. The balance of the boat was designed by Amel with generator on port and lead batteries on starboard and it is seriously impacted by removing circa 250kg from the starboard side when changing to lithium. That's why I am so interested right now in comparing different flavours of lead batteries in an attempt to optimise my performance without moving to Lithium. My generator is in good condition with thousands of hours left on the clock, so for me, the balance issue is the deciding factor. Maybe I end up with lithium batteries and lead ingots until my generator dies! :-)
Alex, I believe you have the "advantage" of needing to change your generator and I think this brings opportunity to maintain the balance of the boat by carefully selecting a generator system which is sufficiently lightweight to allow you to change over to Lithium and also maintain the balance of the boat. The generator which Bill K installed looks very nice. Good luck with whatever solution you choose.
Matt, Ah yes, I understand Amel prefer Victron Gel or AGM batteries? Are you happy with their choice?