In my experience, yes, the lack of a blood trail has been the largest issue. The vast majority of the time they fall in sight. When they don't, that's where it becomes a problem in the thick woods that I hunt in the south. I've found that bumping up to a 6mm with specific ammo (berger 108s) has solved that problem and it looks like the new TMKs might be even better. My son still shoots a 223 though.
We've had one deer out of about 10 that we have had to track after a 77tmk shot because he went rouge and shot it in the wrong spot due to a heavy quartering angle that he hadn't experienced up to that point. The deer was hit but there was no blood to be found and subsequently, we did not find that deer. Unfortunately, it was the largest buck we had seen all season. This was an issue with shot placement 100% but there wasn't much room for error.
I don't really consider a 6.5cm to be small. I shot one deer with a 130tmk this year and it was one of the nastiest blood trails I've ever seen. I don't think I ever had to stop walking.