yeah lfr is viable, it's pretty much the main route. you can do t14 raids or heroic scenarios, but other than that there's a few "ok" VP pieces, but the ToT LFR gear is still better than anything you can get outside of ToT normal/heroic as far as I'm aware.
It's definitely viable. I was a 25 man raider until the first tier of MoP, when I decided to stop. LFR kept me geared well enough to rejoin the raiding community in ToT.
Make sure you only spend Valor on the Throne of Thunder Valor Pieces. These are 522 and the rep is very easy to get. Especially the neck, ring, bracers and trinket. If you're having a tough time getting to 480 to run Throne, you can fill some slots with pvp items (476) stat wise you won't lose anything except on trinkets.