The last few months I have taught 3 Liquid Metal FX certification classes.  At each class I have arranged to have a representative attend from one of the top rated sander companies.  Mirka, Festool, and SurfPrep so far. Below are my thoughts on each one.  If you are thinking of purchasing a new sander, reach out to the class attendees to hear their thoughts as well.  Keep into consideration that these have been used to sand/polish metal.  I should also mention that all 3 have great sanding adhesives, although the SurfPrep was the best. If you also do a lot of sanding on wood, you may want to inquire with the manufacturer to find out which of their systems is good for both metal and wood.   SurfPrep   SPESS3X4CV Price: $300+ depending on size and accessories. Pros:  Small unit that is super easy to hold Low vibration Fast sanding Square design is great for corners They have attachments for most other extractor brands. Fantastic on wood.  In a test, it sanded a cabinet door in a breeze