.270 is a nice caliber for deer. I like the .243 as well, that one takes some care if you are a reloader though. You can overload it or use too fast a powder and end up blowing out a case. But either way the reduced .308s are great flat shooters.
Interesting thing about crossbows, it is easier to miss with one of those than with a bow. I wouldn't have thought so but after talking to several experienced bow hunters that seems to be the concensus. The bolt, even with the increased power of the crossbow, is not supersonic. Crossbows tend to have a distinct "thump" to them when they are fired, and deer will often jump at the sound of it. They hear it and react before the bolt gets to them. A compound or long bow, while having less power, is quieter. Particularly if you are using a silencer. Never seen one on a crossbow, although somebody may make one by now.
Yes, I would need to talk to a bunch of bow hunters to see if the tracking system would really sell. It would cost about $600 to get started because you have to buy the receiver. But the transmitters are relatively cheap, like in the $40-$50 range. Being a hobby guy, I know for a lot of outdoor people this cost wouldn't be a big deal. Think of all the money spent on stands, camo, scent blocker, cameras, etc. I don't do any of that. I stalk them, and I get close enough for a clean bow kill if I hunted that way. But alas, I'm a rifle guy. I'm not even interested in shotgun season.