Echo,
You raise a good point. Sammy may prefer your rationale in the end... "good enough" does indeed get the job done.
I am aware of various manufacturers' 210 Amp machines. I selected a 250 because its about the smallest standard power supply which can attain every [non-pulse or other electronics imposed] mode of transfer on steel, and it will give Sammy more heat input for any serious Al work he may decide to do. Sammy's never responded with answers to the thickness of the work he's planning to do, or the other questions, so you and I both remain at a disadvantage.
There's some psychological phenomena I'm trying to work around with the thinking behind my opinion. One is that blindly paying more means better equipment... it isn't true. Another is more amps is better... it can but isn't necessarily true. Perhaps the most important is that the buyer often has little concept of the implications of his choice (relating here to how expensive or convenient versitility might be) In this case those fourty or so extra Amps push the upper limit of the welder to the lower range of practical spray transfer; it can lead him where a 210 cannot go.
Although a 210 cannot match the process versitility, if he will never use it, and is disinclined to ever be able to with this rig, it's a waste.
Unless extra energy (and duty cycle) will come in handy on aluminum, and it well might, I would tend to agree with you that the money he'd spend would be better put toward consumables and accessories.
Frankly I'm not sure a semiautomatic weld process such as GMAW is appropriate for Sammy. It's real strength lies in it's ability to lay down weld bead efficiently... the high rate of deposition translates into production efficiency, lower product cost, and higher profit at the end of the day but it leaves a lot to be desired when you want to switch between one filler and another, swap gasses, guns, feed rollers (sometimes liners) and so-forth... the cost of a wide selection of GTAW filler rod and tungsten is negligaible by comparison and much easier to store without corrosion or deterioration. Should we presume Sam is aware of this?
It's hard to figure out how to give sound advice.
Anyway, Sam seems to have scramed... I guess all we can really do is wish him luck.
I hope you see I wasn't simply trying to steer him to the biggest box his bucks would buy.
Regards,
d