I thought the wire feed on the SIPs was really rubbish. You need constant feed otherwise you get horrible welds. The problem with these is that the low voltage for the motor that drives the feed comes from one of the big welding current transformers, so everytime you strike an arc and the voltage drops, so does the speed of the feed. TBH, I found it unusable compared to the machines I was used to.
I attempted to fix it, with not much luck. Replacement feed units can be picked up from decent welding shops, but I think putting in a seperate power supply and regulator would go a long way.
I think no-gas is better for most home use. Those tiny gas bottles are a pain, and really expensive. Shielding gas also gets blown away with air movement, so for outdoors, no-gas is better.
I can agree with most of the comments already. Those welders are resonably good for the money.
The wire feed is not perfect, but replace the wire liner on a regular basis and keep the umbilical straight when you are welding (i.e. move the welder so that it is straight behind you so that the umbilical is not coiled up on the floor) and it should be better.
Also recommended is hireing or buying a large gas cylinder if you are going to be doing a lot of welding. Much cheaper in comparison to those tiny disposible bottles.
The wire liner is a thin PTFE plastic tube which carries the welding wire from the welder to the torch. It wears out and makes the wire harder to push up from the welder.
MIG can make good welds, but varying wire speed makes them impossible to do. It can make learning extremely frustrating.
Home-use - irregular use (less than weekly), light duty use, not very thin metal, in the open. If like most home users, you'll buy a welder and use it less than 3 times a year, then no-gas is an easier option.
The gasless ones have a flux cored wire, so it's like a stick turned inside out. The weld is about the same quality as with gas. Because the gas is created closer to the weld, it doesn't get pushed away by air movement as much, so it's better for outside work (but not as good as oxy or stick for windy conditions).
The flux cored wire costs more than the normal wire, but less than those small gas bottles will cost you.
That was the other problem I remember - the wire spool fits in the top horizontally. Friction can cause problems. I found smearing it in engine oil helped, but then the wire overan when you stopped feeding, causing tangles. They also don't take the big 5kg spools which are much better value.
that little mig welder is the perfect thing for badboying, make sure the surface is free of paint and nice and clean. i'd recommend doing it indoors because the clean metal will oxadize faster outside, so borrow a bonnet if you can
i might have to get one of these "flux" welders, i've been looking at welders after i did my welding course but the gas ones are sooo expensive... but gasless are more apealling now