I'm aware of the various tweaks to get the old model to play 1080p videos from a network, but even after tweaking, there are reports (like this one) that it still stutters on high bit rate files when played over NFS or SMB. Larger Blu-ray rips that have large or multiple audio streams apparently push it to its limits, and from the reports I've read, ethernet seems to be the limiting factor.
I'd like to hear from people who have seen the Pi 1 struggle to play demanding videos over ethernet, and tried the same videos with a Raspberry Pi 2. Has anyone reading this forum done an A/B comparison between the two models? What files gave you trouble with the earlier one? How well did the new model handle them?