Not off topic at all. What would you rather buy, a new fangled inverter with a lot of complicated electronics to potentially go bad and be expensive (or not cost effective) to repair or a time tested transformer that has a reputation for lasting 50 or more years and only needing the odd inexpensive repair? There's a good reason Dialarc's and Idealarc's were extremely popular in schools. They stand up to abuse and are great machines to learn how to weld.
I don't know if there is an all in one that has high frequency AC for Tig welding aluminum. If Mig aluminum would be OK, there are a few choices. A lot of people prefer to have separate machines in case something goes wrong with a single machine. When I bought welders for what turned out to be a bad mistake (thankfully a couple friends bought them off me), I bought an AC/DC Tig/stick machine and an all in one Mig machine. Many Dialarc's had spool gun hook ups but the control boxes to run the spool gun got to be too expensive. Sometimes you find them used and they can work off any CC machine. Now most self contained Mig machines have a direct connect spool gun. If you want to run Dual-shield something like a Lincoln 350MP might be a good choice if you aren't doing heavy production. Voltage sensing wire feeders like LN25's can run off CC machines at higher volt settings but the welds don't have the same mechanical properties as they would have on a CV machine. Most of the newer welding machines have a ton of electronics in them that can be great features or the cause of great frustrations. I was talking to a welder repair shop and mentioned the Excel power option on Trailblazers. When it works can save a lot on gas and engine wear but the shop owner said they are very problematic and expensive to fix. I got the feeling it was more trouble than it was worth. Great when you have warranty but after that, yikes!
I don't plan on heavy use. Small repair jobs, maybe fabricate some custom exhaust for my bikes and projects. I have a 110 volt MIG right now and honestly its useless for anything heavier than sheet metal or exhaust pipe. Don't really plan to go much beyond 1/4" plate.
You need to state which machines you've had and now have to qualify your statements. Something built up to 2018 is hardly an antique. Some of the best welders ever made are antiques and still in demand. As far as being tolerant to voltage fluctuations transformers have at least 10% line voltage compensation. The welder I'm selling also has capacitors which further help to handle power fluctuations. There have been problems with inverters being damaged by power fluctuations. Inverters are smaller and can be moved around easier but it's still easier to use longer welding cables. If you move the inverter closer, where do you put it, on the floor? Who wants to get on their hands and knee's to change the amps? If you have a cart it takes up a bunch more space. I have a very good transformer welder I'm trying to sell. It's perfectly capable of any type of heavy equipment repair or general fabrication using stick electrodes. It will also do scratch start Tig on steel. As an added bonus it also has AC current if you encounter arc blow burning larger rods or welding around irregular shapes. A high frequency could be hooked up for AC Tig welding as well. You see them used fairly often. A welder repair shop here has an Idealarc 250 for sale for $1200. It requires 575 volts and doesn't come with any cables or power cord. I don't think my price is unreasonable. I'll also include some lessons and delivery within a reasonable distance. Who else does that?
I worked at a shop that bought a brand new Dimension 452 for me to use. They had about 6 of them and a Lincoln DC 400. I'd never complain about having a Dimension 452 to do x-ray quality welds whether it was Mig roots, stick or flux-core. Prefer them over XMT's for Mig.
It was a great machine. We were welding up to 1.5" plate along with hard facing wire. I never welded the heavy stuff, I did more of the smaller stuff.
