The Can Tire 6v is a very good GC15 230AH at a very good price and would do you another round on the 5er with the same success you have had in the past. Makes no sense to change to more expensive batts unless you have a "fever". ( Like when you want a new car :) )
The price of the SiO2 is somewhat negotiable. I got the second one at a big discount compared with the first. You get more of a discount if you buy more at a time. You have to talk to the person at the shop and ask for a quote. You can suggest you would be interested if only they cost X. It is like a bazaar. She says you are trying to starve my children, you say I can get those Can Tire ones for a lot less so I am doing you a favour buying these at all. You find out the real price, then decide.
If you have room for regular 6s or whatever in your RV there is no reason to get SiO2 or Li.
If you have a smaller RV and you want more AH, but no room for more batts, now you have a proper reason to see if the more expensive batts would solve the problem. Another reason is not just more AH but being able to run high amp inverter draws with the small battery bank that is all you can carry, which you can't do with the small bank of Wets or AGMs.
BTW it amazing this thread has not been moved!