[BenMcr]

All depends on your preferences and the situation.

For instance CBS Action is SD only, however shows Star Trek from time to time. SyFy show Star Trek in both SD and HD when they can. What they show could be the same version of the show but in different seasons.

So you can choose if you'd only want to record the quality of the show you'd prefer for either viewing reasons or disk space reasons, or as you say get whatever if best available for your other series link choices.

Same applies for NCIS. That's shown across both SD and HD channels at different points. So being able to specify the quality alongside the other options can help ensure you get the episodes you want.