I have never used anything but the flat blades. So o can't say. I would think if you are cutting pasture grass or open meadow, I'd opt for the high lift blades. It if doing lots of brush, saplings, briars, etc I don't think it matters.
And check eBay. There is a company that sells on there that usually has tons of closeout blades for obsolete or discontinued models. Prices under $5 each. Look at the dimensions and see if you can find a match. I did this with my bh306 cutter. Blades matched but we're just a tad long. No big deal to cut them down. But got 3 sets for something like $60 delivered. And $40 of that was shipping