RE: Best Rangefinder for around $300
TBR is certainly real and can have a great effect at longer range rifle shots. I'm not as fimilar with the effects on a bow, although I know it does exist.TBR is a large part of physics, it can't be argued. There is also an easy way to create your own TBR type cheat sheet. If you can tell me how high up yourstand will be from the ground, assuming your in a tree stand, and how far the deer, or other targetwill be from the bottom of the tree, I can calculate a TBR range for you.
And yes, other range finders work fine uphill and down hill, but they will just calculate a straight line distance to the target and they won't give you a ballistics range for uphill or down hill shots. Shots with a steep angle will always require the shooter to aim at a shorter distance than the actual straight line distance.