[Solved] What is the best spool holder alternative?  

RE: What is the best spool holder alternative?

@flood

As for me, the point of the high speed printing was mainly for draft mode.  For instance, in making a drag chain adapter and related wire guides for my CNC, I'm finding it to be a very iterative process.  One of the parts takes over 8 hours to print with a 0.4mm nozzle and the default 0.2mm layer height Quality setting in the Prusa Slicer.  That really slows down the iterations!  For that purpose I'd gladly trade detail for speed and yet still  do the final print with more detail and less speed.  On the other hand, what I really want is a printing appliance that "just works," not a test bed for developing my own 3D printer.  So, I'm tending to stick with the stock build, as upgrades are easier when Prusa releases them.  I am presently using a 0.6mm nozzle, not a 0.4mm nozzle, and, like you, I do use the real-time tuning to increase the speed to 200%, which by itself maybe reduces print time by 1/3 while introducing little risk.

I did like the V6 volcano upgrade and the 0.8mm nozzle, but it's a non-standard build, and switching back and forth was a hassle.  I think the ideal setup for me would be a very fast printer (maybe a corexy) for iterative drafts and a separate i3 or similar for final prints.  That way there'd be no hassle or time lost switching setups.