I used a 4x6 for many years, and was constantly fighting it.... It "worked", but there was always a lot of effort put into each use.
My first Porta-band was a Milwaukee, and I was sorely disappointed. It was loud, the blade was jumpy, and it would overheat (thermal shutdown) after about 10mins. of cutting. I took it back a couple of times, but was always told "it's fine". Finally, the idler wheel hanger went bad, and when I tried to send it in for warranty, I was told "it's a design issue, not a warranty issue, we won't cover it". That was less than two years into Milwaukee's "5 year Warranty".....needless to say that I no longer buy or recommend Milwaukee tools of any kind.
I went with a Dewalt, and could not be happier. It is head an shoulders above the other metal cutting saws I have used. Here's a few photos....
This little saw is great for the sawing jobs I encounter in the finish shop....about it's only drawback is the throat depth. I solved that issue....for bigger cutting chores I have a 7x12 Wilton, wet/dry saw in my Blacksmith shop.
The one conclusion I have come to after all these years is that when it comes to metal cutting bandsaws, there is a definite need for two in most serious shops.....one for small jobs, and another for big jobs.
I think the majority of 4x6 saws are built with the "hobbyist" in mind....someone who only uses the saw occasionally.