My experience of two 250's belonging to two different people is thus:
They are a good welder with decent reliability, but you do need to be aware of there pitfalls which are,
The standard MB25 torch (3m) supplied as standard is a below par and they wear quickly, on both machines I have seen and used they were swapped when worn for a quality replacement.
Standard supply regulators are best stood on concrete and repeatedly hit with the largest sledge hammer you can beg steal or borrow, replace with a decent 2 stage unit and fit a pea shooter.
Earth clamps should be treated the same way as the gas regulators and repeatedly hit with a large sledge hammer and replaced with a decent 400 amp type.
As far as welding performance goes, well, a lot comes down to the skill of the operator, they are no better or worse in there welding ability of those in the same price bracket and those in the price bracket above them, they all need fine tuning and fine tuning is the key as with all MIG's and its easy to get them to operate in dip and spray mode and again this is operator skill. I have welded plenty of U/C with them when one of the owners wanted a small portal frame and they do a decent job of attaching base plates and various other support brackets with plenty of penetration.
One owner has had his for 5 years, the other 6.5 years without issues.
My advice is thus, learn how to set them correctly, replace the original gas regulator and earth clamp as above, and use the original torch until worn and replace with a quality replacement.
Totally agree, you have already swapped to a 15 and got a 2 stage regulator unless yours is a 180 and not a 250 I believe they came with a 15 as standard, but I could be wrong, they only use 15Kg spools on there machines so you have taught me something.
I just recently got a 2 stage Esab reg and the saving in gas has been quite dramatic. Press the trigger and the gas goes to the flow rate set instead of a second or so surge at a much higher flow rate.I like all of the above ^ except, never have we ever used 2 stage regulators on welders ever, and never had an issue. A half decent single stage works fine on a MIG set, and we use single stage + flowmeter on TIG sets.
I've never heard of all this 2 stage regulator hype apart from on this forum.