What would be the best scope for a T/C pro Hunter 209x.50? I know that 150-200 yard shots are possible. Does anyone use a fixed power? i.e.6x42? Whitetail hunting with consideration to low light conditions will be the primary use of this gun.

Started out with M8 6x Leupold on my first inline, only problem close range it was a bit limiting. I have since used variable rifle scopes and never regretted that desicion. I have shot deer from 30 to 230 yards. I'd personally suggest a3x9/10 x40mm. Which one depends on what you have in the budget:
$200 range Nikon Monarch, Bushnell Elite, Burris FFII 3x9x40's
$300 Leupold VX II 3x9x40
$400 Zeiss Conquest 3x9x40

I bought a 3-10x50 MEOPTA MEOSTAR. I went to cabelas and looked at the Swarovski A Line, Kahles CL, the Nikon with BDC and the Meopta. I think I got the best value for a truly quality optic. I thought it was superior to any of ther others. I know it is a big objective, but the bucks aremoving in the low light. This scope was as clear as anything I have ever seen. Now I need rings and bases. I am looking into the Talleys, Warnes and Eabco.coms interlock. If anyone has any suggestions and advise, I would like to hear it before I spend my money.

My son has a Zeiss Conquest 4.5-14 on his Encore ML, and he loves it. He has the same scope on his Encore 270 too. If you don't like that much magnification, I would go with the 2-8 or 3-9 Conquest. I have owned many scopes from Tascos to high end Zeiss and Swarovski, and for my eyes, the Conquests are the best optics for my money.