I haven't used steel in ML's, but in fact when the requirement for steel finally came to Alaska it forced me to quit ML waterfowl hunting after many years at it. I don't have any problems with steel shot and it's performance on birds, but at that time anyway and with components then available, it was sure going to be hard on shotgun bores.
I'll be watching this thread closely because I'm dying to get back at it, but not when the shot is $170 for 7 pounds. Sheesh..... Or words to that effect.
BTW- Some unsolicited advice. That article is pretty well right on in the fact that steel can do the job on waterfowl when you use it right. At the ranges I shoot (less than 40 yards, and usually less than 30), it's a stone killer.
But..... I repeat- BUT!!!
I'd pass on the advice to jump up two sizes, and instead go three sizes. And I'd pay lots of attention to high velocity. My normal lead shot load was #6 at around 1100 fps. But optimum performance on ducks with steel didn't really surface for me until I went to #3 shot for most of the season, then #2 late in the season with heavily feathered birds. It also kills better and better, the faster and faster you throw it. When it comes to a tradeoff between charge weight and velocity, I'll take velocity every single time. The heck with those heavy 3" mag charges going slow. I want the 1 1/8 oz charges smoking out at 1500fps. Even better is a 1 oz handload going faster. You might as well take advantage of the great patterns by lightening the shot charge while popping the velocity.
For geese, I'd go ahead and buy the Hevishot or potentially cheaper, the Tungsten Matrix shot such as Kent loads in their shells. In my experience even T shot in a 3.5" 12 gauge shell is marginal for geese at 40 yards. The pattern gets really thin and the shot don't penetrate well. Lots of crippling. But the size #2 tungsten matrix Kent loads kill like lightning at 40 yards!!! Even in a 3" shell. In a 3.5" load they're reliable killers even further.
In the lead shot days my normal muzzleloader range limit for both ducks and geese was 30 yards. I'd stick by that if I used steel today, and probably wouldn't feel any handicap for the change in shot.