Rule of thumb, operated properly, one Horse Power will cut one cubic inch of mild-steel per minute. The Warco Major has an 1100W motor, so it has the potential to cut about 1½ cubic inches of steel per minute. Don't!
'Operated properly' means cutter in good condition, at optimum depth of cut and feed-rate, with cooling and lubrication. The rule of thumb also assumes the machine is rigid enough to make the cut without bending, the drive train is man enough to take the strain without breaking, and that the motor is rated for continuous operation.
Industrial equipment is heavily built to meet these requirements – one reason it costs 6 to 25 times more than hobby gear. Hobby equipment is relatively lightly built down to a price, designed for intermittent cutting at moderate rates. (A 300kg Warco Major is lightly built!)
Most hobby mills can cut steel. The very light small machines used for model railway and similar work are the exception. Intended for quietly machining Brass, Aluminium, Wood and Plastics on a small scale they're not very rigid, the motors are small, and they run at high speed. They're good within their limitations, and can be operated inside the house. Although they can attempt steel, it's out of their comfort zone. A Warco Major will happily cut steel but is too loud, heavy and messy to run inside a home – separate workshop needed. It's not a production machine – don't expect it to cope with Piece rate work in a Victorian Sweat Shop.
All milling machines have limitations. Sadly I don't have room for my heart's desire, a Bridgeport. Much more capable of hard sustained accurate work than a Warco Major, yet Bridgeports are considered flimsy by big mill standards…
Dave