If you have money to burn and don't know one end of a screwdriver from the other, spend the $$.
Otherwise read the fine print in close detail. Typically things that don't break are covered and things that do, aren't. Best thing is to stock up on some basic tools and some spare supplies (plumbing fittings, electrical connectors, screws, tape, etc., etc.) and fix things yourself.
Even if something is covered, your TT could sit on the dealers lot for many weeks while they fix it to suit their schedule, not yours. Not good in the height of the camping season. And too many dealers are inept and can't fix things properly it at all, even if you tell them what is wrong. (BTDT too many times.) Doesn't matter if it's the factory warranty or extended warranty. If you happen to be far away from home in the middle of nowhere, you're going to have trouble getting to a dealer that will work on it - another reason to have some tools with you. You just never know what will go wrong while you're away on a trip, and it does.
I'd keep your $$ and buy some nice RV accessories instead. :) Or put it towards a good roadside policy. What would happen if your TV broke down far away from home? Would towing be covered for the TT and/or TV? Not something we thought about much until recently when the engine in our truck blew up 5 hours from home.
The insurance policy we had at first was a premium one with some nice extras. If any appliance needed repairs, the TT manufacturer's warranty (2 year) was doubled, so we got 4 year's worth of warranty on appliances. Never once had a single issue with them and never needed the extended period. No wonder they can do that. Appliances aren't something that routinely break.