That is a hard answer without know your camping style.
Do you always camp with electrical hookups? Have you ran the batteries out of power while you are out camping? Do you plan to boondock, or maybe boondock more often? What type of frig do you have (120V residential, 12V DC, 2 way Propane/electric)?
If you have had no issues in the past, stay with what you got. One thing about lithium batteries they do weigh a lot less than LA batteries. So if weight is an issue, lithium might be an option.
As for what is entailed. You need to determine what converter you have in your MH supports lithium batteries. Some converters of that era have a switch that you can flip from LA to Lithium. If you do not, you just need to replace the converter unit to a lithium prepped unit. Not a lot of work.
Good luck!