The 4 piece bonus is VERY good. You might consider taking HC Warforged pieces over LFR tier pieces, but 4 set at the normal quality beats all.
AskMrRobot is a tool, not a guide! It comes up with some numbers out of the box that aren't too far off track, but might not fit with your current gear, talents and playstyle. If you want accurate results from AMR, Sim your own character first!
Download from
http://simulationcraft.org/Extract and run.
Go to the import tab, copy your armory link in the URL at the bottom (you do NOT need to log in, so I recommend not to), and click Import at the bottom right.
Go to the options tab, and the globals subtab. Change the TMI Standard Boss to T16H25, the TMI Window to 6, and the TMI Actor-only to Enabled. You can change some other options here as well, such as iterations and threads.
Go to the scaling subtab and change Scale Over to TMI. Be sure to enable all weights that would have any impact.
Click Simulate at the bottom right, then go take a coffee break, as it may take a while.
Eventually, it'll complete, and give you proper weights that fit your character's gear and talents (though maybe not playstyle). Fill those weights into AMR, and then check and see what AMR advises.
If you want to be sure if an item is an upgrade over another item, go to AMR, change your gear and gems around, click SimC at the far right, and copy the entire block of text.
Go back to SimCraft, to the Simulate tab, and paste the text in either an existing or a new tab, then simulate again to compare your new TMI to the old one.
As for Jewelcrafting, it's in a crappy position right now. Secondary stat gems are so good in MoP, not because secondary stats are so amazing, but because you get twice the amount of stats. Jewelcrafting however only gives you once the amount of stats extra, so the jewelcrafting perk is bigger on primary stat gems than secondary stat gems. This forces jewelcrafters to use primary stat gems to get the maximum out of their profession, which makes them fall behind on other professions.
Dodge is usually better than parry for us, even though dodge is on a higher DR, because we get so much parry from strength. However, since both dodge and parry are poor stats for paladins, we usually don't care and reforge out of both of them. If both are present on a piece, reforge whatever there is more of, as it gives you more Haste.