I started with the most modest of printers - the Anet A8 - and gradually upgraded things as I learned. Today about the only things left original are a couple of end switches, some screws, two lead screws and an extruder motor. I moved to a Duet 3d mainboard, everything is 24 volts, all metal frame, linear rails, etc. The Duet and going 24V allowed me to power a good bed heater and now I nearly always print at 110C (I print PETG almost exclusively).
At 110C, PETG sticks great. I did some nylon prints a while back and used 110C with glue sticks (something never needed for any other material) and I got good adhesion.
For my bed heating element I got the following from Gulf Coast Robotics
Silicone Heater 200W with Integrated 50K Thermistor for 12V or 24V 3D Printer Heated Bed (200x200mm)
Speaking to one of the folks there - really really great guy named Brett - the adhesive is probably good up to 140C but not beyond that. I was getting advice on printing polycarbonate at the time (still haven’t tried it) and wanted a bed at about 135C.
In terms of bed leveling, I have a BLTouch and can get great results with and without it. Keep in mind the mechanism of auto-levelers is to make minute adjustments to the height of the print head at every spot on the board. So, you are conceptually creating some moving parts if you know what I mean. I probe 100 points and find that now, a few years in and being able to level a bed, I get just as good a set of results without bed leveling. In fact I have an important 24 hour print that I just started and I did not turn on auto leveling. Without is more predictable. The big thing I use it for is to do a bed scan to understand how good a job I did of manually leveling.
I have experimented with duel extrusion and my biggest issue was keeping both nozzles at the same distance from the bed. Never got anything I was proud of - if I wade in again, I’ll try an E3D Cyclops type setup instead of an E3D Chimera type setup. Seen some other designs that looked like they would address the issue of keeping the nozzles level. I’m sure there are some good approaches out there.
Hope all this helps. I think my summary is that with a 110C bed you can do Nylon and that yes, there are pounds of people who swear by bed leveling but many others who take it or leave it, or at least can do without it.
I’m not qualified to speak to any of the exact setups you are evaluating. I’ve been more the DIY road which is fun but much slower (at least for me). If you don’t want to do tons of DIY, you could find a model and see if there are mods for bed leveling. Sort of a “get most of what you want and mod the last few things” approach.
Good luck and have fun! Yell if you want more info.