I replied to another post with a list of mods, so take a look at the other comments in the post for some out of box mods.

As a 350 owner, be aware of two things.

First, big bed = big chamber = heat soak takes a while and you have a lot more surface area to lose heat from. If you want to print big ABS/ASA parts you’re going to want ACM panels, a better sealed/insulated front door, and potentially a radiant layer inside the printer.

Second, the big printer limits your rate of acceleration some compared to a smaller CoreXY. IMO if you have a big printer to print big things you’re probably not going to have small/finely detailed parts that often. Those are the kinds of parts that will go a touch slower. But honestly 5k acceleration is orders of magnitude faster than most bed slingers can achieve and 10-15k is only a 2-3x increase so you’re not giving up that much.

Other than than, no regrets about the 350.