I am considering the purchase of a Nikon 2.0 teleconverter for use with my 70-200 vrII. I would use it for outdoor sports and also for low light basketball in which case I would shoot at a fairly high iso. Any advice or experience will be appreciated.
Assuming that you are considering the TC-20E III, it will work well for shooting outdoor sports in good ambient lighting (daylight). I think you will be dissappointed using a TC for shooting indoor sports like basketball. Especially in poor ambient lighting. In many venues you will be shooting at ISO 3200 - 6400 even with a 2.8 lens wide open to get a shutter speed of 1/250th - 1/500th sec. With the TC you will be at f/5.6 which gets you to ISO 12800 - 25400 and AF will be very slow if it works at all. Besides a 70-200mm on a DX body should have more than enough reach for shooting basketball in even a large gym.
Just a thought. The TCs all cost you light. The beauty of the 70-200 f2.8 is that it's fast. If reach is a problem there is another approach. The 7100 s a little more than a TC, but you get a lot more in the bargain. The 70-200 is still 2.8 and the effective 300mm is still 24 MP. You can crop the heck out of it. I love that combination.
It was only after I understood the 1.5X aditional zoom for DX format cameras, that I understood this!!! This is true for same Mbytes cameras, the size of the pixels will be the same after zooming the DX image to FX size.