For now. Glowforge may change that setting at any time.
Also, I suspect that you are overpowering your cuts. MDF is a fair bit harder to get through than birch layers, so it doesn’t surprise me at all that you’re getting reliable cuts. For example: looking at my pro, I currently see 170/full coming up as the medium basswood plywood setting, whereas I cut my BB very reliably at 205/full, and a little less reliably up to about 215/full.
So, who cares? Why are those 35 speed points important? Well, at 170/full you’re tearing the wood up more than you need to. On tighter cuts and finer details you’ll fry your materials a lot more than is necessary. The edges of BB get darker and darker with slower cuts, so your BB edges will be very dark indeed at 170 versus 205. Lastly, it’s significantly slower.
So, doing a material test and zeroing in on the fastest speed you can get reliable cuts with will pay you back in time, materials, and maybe aesthetics if you want lighter edges.
See #6 for my cut testing method.