I sold my Mk3 and ordered a Mk4. My reasoning was that, if I buy the upgrade kit, I will have many unusable parts, which are technically still good. By selling the Mk3 for 300€ to a colleague, I got about the difference between full Mk4 and upgrade kit.

Did I miss something in the MK4 announcement? I thought the MMU was compatible with your MK3S+

For the MK4 stuff, I need to see an independent person do a side-by-side. I'm sure it's better, but I'm not sure it matters enough to me, a casual, to spend $hundreds.

I have a 3s+ and a 4. As it stands right now my 3 has been much more reliable and is still my go to machine. I feel like the 4 still needs polishing. I have to fiddle with the Z offset here and there depending on my filament and the input shaping alpha is neat, but the finished product on the 3 with a 0.6 nozzle is much nice than my 4 with input shaping. Knowing what I know now I would rather have 2 well tuned 3s.

The upgrade is expensive enough it may make sense to just buy the MK4 outright and keep the MK3 as a second printer. I haven't done that yet, but it's a definite consideration.

I’m tempted but not sure it’s a wise financial mind at the moment… but I’m definitely tempted! 😈

I was tempted to do it, but I got my 3s tuned where it produces parts I'm happy with and largely trust the 1st layer, building a Voron v2 instead (also to get a larger print area) and keeping the 3s as a known good reliable printer, likely to be what I'll use for abrasive filaments as I've already got it setup for that.

I'd love if prusa put out component only kits tbh, I've reprinted everything in abs/Asa as I do a lot of abs printing and had the original petg X axis idler fail on me so I'd really like to have the option to provide my own printed parts, or even being able to choose material types. Working on putting a SMuFF together instead of grabbing an mmu3 for partly that reason.