Well I had no third party problems untll I changed from D7000 to D7100 and D800 and yes I know Nikon only have to support there own products but it would be nice to know whats a good buy and what isnt.
Fitted my sigma 18-200 and 18-250 to my D7100 (I have a pair) and all seemed fine until I noticed the LCD was on a long time..in fact it would not go below 60 sec ..battery life down to 1/3...sigma said it was a feature All sigma lenses off to Ebay ..never buying another.
Purchased a 3rd party Neewer grip for each of the D7100...worked fine but whatever battery you set to discharge first the one in the camera was used first while the shot count was on the grip battery..Strange ..never discovered if it would change over .Now I just just use one battery only in the grip.
Now the Neewer grip for the D800 was different ..if you turned it on you lost all LCD functions !!!
Third party batteries that worked fine in the D7000 would not work with D7100...but 3 of the 7Genuine EL 15s I have owned have gone bad.
YN 565 ex worked great with the D7000 but with D800 and D7100 locks the camera at 400 iso even when its off ..ie the auto iso does not work.
The people who I feed sorry for are those who udate firmware "because its the thing to do" and loose functions they once enjoyed with there 3rd party accessories..