You didn't mention how far you may be shooting thru those Blackberry Bushes and what you might be shooting at.
The Whelen is a heavy hitter, and works good as a brush buster. But if your longest shot may not exceed about 150 yds, the Short Action .35 Remington would do just as well for Deer sized game. Sometimes it is hard to see more than 75 yds when you get into those thickets, so having more powder really doesn't do you much good. Also, when you are in the thick stuff, you should realize what your closest shot may be. Some long action calibers are too over-powered at close range.
Going for big Bear at any distance would certainly warrant the long action Whelen. Then again, a .30-06 with the heavier loads would do just as good.
I have toyed with the idea of buying a Whelen, but so far I haven't. I think if I were to hunt for Bear here in Pa. I would buy a .444 or a .45-70 Lever and leave the Deer hunting to my .35 Rem or the .308.