First, both o-ring and non-o-ring chains are roller chains. They are essentially identical items, except the the ring chain has an o-ring placed over the pins on both ends.
Most all of your top shelf chains today go through a "proof stretching" process during mfg'ing that places approx 60% of the total rated pull on the chain. This procedure will stretch the plates out and let them find a home.
Contrary to some's belief, chains do indeed stretch before any wear at all takes place. This lengthening is called "initial stretch". Until mfg's started proof stretching chains, the intial stretch would occur during the first hour or two of hard riding and immediate adjustments were called for. This is pretty much a thing of the past. If you have a chain that is growing fast, and it has been proof stretched at the factory, then you have either an adjustment (most likely), a cleaning, or a lubrication problem.
Even if the chain hasn't been proof stretched, you probably are not seeing initial stretch if you have to adjust mucho. Other than the side plates elongating ever so slightly, a chain does not "wear in" unless it is of very low quality with poor tolerences.
I have to agree on the standard chain being the best all around choice for most of our riding. A ring chain should be mounted when you ride in the slop all day, but remove it and put the standard back on the rest of the time.
Folks get too used to thinking their ring chain is maintenance free, until it does indeed have at least one reel frozen up. And as described, the sprockets will go fast at that point. You will rarely see a standard chain, that is well maintained, do this. A ring chain that is taken pristine care of can and will do this. It's a matter of not being able to always protect the rings from damage. Once one ring is violated, the chain and sprockets are on a downhill slide.
Matt....are you sure the MRD is the one with the holes? Did you see this chain?
I'm fairly certain the MRDL and MRD's don't have the lightening holes. I think those are on the grand prix chains by EK, maybe the RX series.