Hi Guys
Thanks for the responses. Seems not too many Raiders going down the Li track. FYI I kept lookinjg and as Kingie Chaser suggested checked out a few 4 x4 sites There were some great recommendation there after 5 years using the SolarKing range with 12V 100 AH going for above $600 ea ("discounted") which seems to be about the mid price point for Li. The specs say can connect parallel or series but just to check this and the warranty of 3-5 years I rang the seller in WA. They confirmed that they would be good for the 24V MK, marine environment, dedicated Victron charger etc and said they would send me a copy of the warranty (which I asked for as some are full of nonsensical "outs"). While waiting for this to be emailed I found another seller in Melbourne (quicker delivery to the Coast) and called him. We had a chat and THEN he told me he would not recommend connecting them in series!!! "What about the specs?" He said there were previous instances that they did not function properly in series because the internal BMS (battery management system) played up! An honest guy who put aside the $1,200 + sale!
I now feel I have had enough and like Grantos and OneAF said, will go a couple of (heavier) AGM's (68 kg) which have to be sited on one side of this boat and before ordering I will check whether this will affect the trim. My mate has this sytem for the same 24V MK and has had no problem with all day on and off, trolling, spot locking in the Brissy currents etc.
Sorry for the long post but it's to warn others that despite what it says in the specs, it ain't necessarily so!