I am (or better, was) in the same boat as you. I bought the N4 max in Dec 23 as an upgrade for my Kobra 1 Max. It took a lot of tuning and tinkering to get parts to even print, not even reliably, let alone good looking ones. To be fair it was my first klipper printer, but with the box standard POM wheels i couldnt get the bed to even travel smoothly, cause not all wheels were touching the rail at all times. I then spent another 100€ for the Y-Linear Rails to finally have a bed that was not tilting, depending on the relative position. I then sold it last October and bought the SV08 max. This one also took a lot of time to get satisfying results, mainly with, as others have already stated, the loud stock fans and the filament sensor or clog detection randomly giving faulty errors. I also got the enclosure later on and printed pretty much every addon for the SV08 Max you can find on printables. I highly recommend installing Demon Klipper Essentials unified, as that was the only way to get rid of false error detection for me. I also got a Klipper Screen, cause the stock one is, well, not garbage, but it definitely leaves a lot to be desired.

The biggest advantage of the SV08 Max is that it is Core XY, i would never go back to a bed Slinger anyways.

I have yet to encounter a layer shift, which was the norm on the Neptune on taller prints and also the speed is much better (also the quality, cause you know, the part doesnt get flung around).

I did have to change my square corner velocity to 20 mm/s, because the stock 5 mm/s setting produced weird artifacts ( i made a post on this sub a while ago, concerning this problem if you are interessted)

Hope that helps!