My car is lowered. I cannot fit a low profile jack under the car in order to jack it to get it onto the crib. The race ramp you have in the pic, no way my car could use that. Why not just get jack stands instead of the crib blocks?
I use these stands in order to get my front high enough to get my low profile jack under the car to raise it and put it on jack stands. My car is not really that low. I don't scrape at all driving around.
A ramp that gets your car higher off the ground is useful because you can do some maintenance that requires you getting under the car without having to go through jacking up the car and lowering back down onto jack stands. However, you have to have wheels on to use it, which means you'll still need jack stands when you need to do maintenance that requires wheels off.
Going with those block cribs just seems like all the limitations of using ramps with none of the benefits for ease of use. You're still going to have to jack it up (..and if you lowered it you'll need a low profile ramp to fit even a low profile jack ...) and you're still going to have to lower it onto the cribs only now you'll have ramps, jacks cribs and jack stands. Seems redundant to have the cribs and jack stands to me. If you're really worried about your jack stands not fitting the BMW jacking loctions, get some jack pads