I've never killed anything with a .280, but have taken more than a dozen mule deer, elk and proghorns with the .270. Eventually I hope to have .280 barrels in the Handi-Rifle and T/C Encore, and when I do I will shoot 150 grain bullets for medium BG and 160 grain Partitions or Accupoints for elk.
The .270 kills biggame VERY WELL and quickly, but it destroys huge amounts of flesh because of bloodshot. For this reason I've learned to like and depend on heavier bullets propelled at more conservative velocities rather than to try to eek out every measly foot-per-second of speed. If i still shot the .270 I would shoot 150 grain bullets OFTEN, but 140 grain Ballistic Tips for long range shots (250+ yards) at pronghorns or LR mulies. I'll never shot 130's in a .270 again - because of the many BG I lost whole shoulders on. Even the 140 grain bullet destroys lots of muscle.
If you stick with the 175 grain pill, you'll kill your deer as dead as ever, with complete pass-throughs 99+ percent of the time. But if it was me (and I hope it will be soon), I'd choose a 160-162 grain bullet for my all-around bullet weight. FWIW.