I too watch Grimm at 8pm now (at least, until the series ends). But on Saturdays I manage to find 45 minutes or so to watch MacGyver on the CBS website.
Best of both worlds!
NBC has a history of abusing good TV series, (they canceled TOS Star Trek back in 1968.)
LOL, I find it funny that you're using a 50-year-old example of NBC's bad judgement. Just goes to show that TV fans have looong memories.
Grimm is the only thing I watch on NBC; I've never cared for most of their programming; that's why Grimm was such a nice change of pace. A lot of my other shows are on CBS.

I use couch tuner.com a free streaming website with no commercials or sign ups.

You can watch the latest 5 episodes of any cbs show on cbs.com for free or the whole season for most shows for $4.99 a month.

You are correct but I prefer DVR over on demand so I can skip over the commercials.I do plan to use on demand to catch up with MacGiver
That's my two cents.

Don't you have On Demand services from your cable provider? That's usually how I watch the show the day after. You can't skip the commercials which sucks but you can watch the whole episode as it aired.