Andrew,

On Chris Schwarz's Tool Blog "Never Sponsored" (Entry may be be behind a paywall) he expresses his opinion on ROS.

https://neversponsored.substack.com/p/sand-without-dust-or-bs?utm_source=publication-search

Marc Spagnolo (AKA The Wood Whisperer) on Festool v. Mirka

https://youtu.be/IuXRRG3Xbys?si=06bztCUMjRUtVgIV

On 6" vs 5" I've had Porter Cable both 6" & 5" - I like the form factor of the 5" even though I thought I'd like the 6" better.  The 6" disks are harder to find but not impossible to get (Klingspore sells them) but if you have to make a quick run to Rocky's you may be disappointed since most stores only carry 5". The internet is your friend here.

Please keep us posted as I'm haveing the internal struggle with upgrading a ROS system myself. 3M, Festool, Mirka, SurfPrep

John

I have the festool ets and like it a lot, great balance and no vibration. you can sand all day with it.  I used my old shop mates mirka some but not a lot, id say its as good if not better than the ets. 

The paddle switch on the top is a game changer, especially if you have used a pneumatic sander. 

Better ergonomics and vibration control is a large part of the cost difference between  the cheaper sanders and the higher quality ones.

Last I knew mirka made the ETS for festool. 

I have heard very good things from fellow professionals about surf prep, but haven't used them at all. 

the shop I'm starting at next week has mirka, I'll have a bit more first hand info then.