I wasn’t really sold on the 4/4S, but I recently upgraded a 3S+ to a 4S and am amazed how much improved. The new touchscreen LCD is a huge improvement over the old two line monochrome LCD. Remote access and wife printing is a nice plus — I don’t even run OctoPi anymore. Automatic bed leveling and no more Live Z tweaking for each sheet has been a major quality of life upgrade and eliminates one of the major pain points in swapping out nozzles. The nozzle is much easier to swap out and is now high flow. Add in Input Shaping and it prints significantly faster.

I hadn’t had any experience with the new platform prior to this upgrade and I skipped over the MK4, but the 4S upgrade is a significant step up over the 3S/3S+. I wouldn’t necessarily recommend the upgrade kit — that took much longer than expected to complete (about two days) and I regret not buying a new printer instead. But, I have a 3S I plan to upgrade to 3.5 just to get the new electronics; that upgrade is far less intensive.

If you haven’t tried out a 4S you might be pleasantly surprised by how much nicer it is than the 3S+.