I started my beekeeping with a hive package and it came with plastic foundation, so as I've expanded I've continued to use it. Some large cell and some small cell, but it all worked about the same.
Later I got some wax foundation as part of a used gear buy and it seemed to work about as well.
A couple weeks ago I started to run out of gear. Between splits, swarms, and a couple cut-outs now, I'm at 13 hives, which is more than I ever planned to run. Anyway, I had picked up a swarm and realized I was all out of foundation, so I figured this was a good time to try foundationless. I picked up a large bag of popsicle sticks and glued them into the groove at the tops of some empty frames, installed them to either side of my remaining two plastic frames, dumped the bees in and hoped for the best.
Today I found they have nearly drawn all of the foundationless frames and just drawn some burr comb here and there on the plastic. Not only did they draw the foundationless much faster, they obviously significantly prefer it to the plastic.
So, I'll experiment some more to make sure this holds true for other hives, but I can't image wasting more money on foundation in the future if the bees react like this.
Of course, this is a medium. I haven't tried with a deep yet and it seems like that may be more fragile.