I had my Midland rebuilt by Booster Dewey and I have been happy with it so far. It cost me $205 plus I think $20 to ship it to them.
One thing I have found on my car is that every single thing that a previous owner changed from stock started a cascading series of changes that made things not work as well or not work at all. Every time I return something to the stock configuration with a rebuilt Ford part or a quality reproduction, I get good results.
Also, having the rebuilt Midland at least retains some value in the part vs. a cheap import part. A midland core is worth around $150-200 I think.
Same experience. I bought a new booster from Stainless Steel Brakes corporation. It never worked well. Got an original Midland booster rebuilt by Booster Dewey - worked perfectly and very happy. It would have been a lot cheaper if I had done that first.