I have the older version of the Brown 416 rotary cutter, it's called the 472. They are incredibly well made and perform as expected. I haven't had mine too long yet, I just got it last fall. I moved up from a light duty Woods cutter and it is absolutely night and day.
They are very comparable to the Bush Hog 296 rotary cutters, which are considered by many to be the 'best', one main difference with the Brown is it uses thicker steel for the deck. It is a very heavy duty rotary cutter even though they call it a 'medium duty' I believe?
I posted a thread on here not too long ago regarding my 472 and my experience with Brown, but it didn't get any responses. I believe Brown would be one of the most sought after cutters if they had some better marketing. Many people have never heard of them and are hesitant to go with a company they don't know about.
I'm not sure what the lift capacity is on the
M6040, but you are probably right at the minimum limit (maybe even below it?) for the recommended hp of the 670 series.
Brown rates the 410 series as 2" cut capacity, but as mentioned before, it is very comparable to the Bush Hog 296 series which are rated around 3 or 3.5" if I remember correctly. Since the Brown cutter is slightly heavier duty than the Bush Hog, it is certainly "under" rated as far as cut capacity goes.
I would call their main number listed on the website and talk with them, they will tell you all about the local dealers and anything about the cutters you want to know. I have a local dealer that I never even knew was a Brown dealer. I've found them very helpful with questions in the past.
I'll try to find my old threads regarding Brown in case you haven't seen them.
You would absolutely be impressed by these cutters, they are incredibly tough, yet with a fast blade tip speed give a nice finish as well, not lawn mower finish, but better than some other's I've seen.