Don't have any personal history with the Rowland but some with the 45 Super.  If the gun is intended for range or general field use then run where your heart and wallet leads you.  But (along with the 45 Super) it quickly becomes a very custom one off gun.  Comes from profoundly exceeding design criteria for the host weapon.  Overcoming all that is, among other things, a lot of fun yet I have read a lot of reliability problems.  Not a big deal for most applications.  But if you are carrying the gun for protection against big and toothy things... a persnickety gun is the very last thing you need. 

While the performance specs of the Rowland are simply outstanding, a 6" Glock aftermarket barrel with Underwood 220gr hard cast bullets is not far behind and suffers none of the reliability issues of the Rowland.  Ammo is available and practice is reasonable.  I know many Rowland conversions run quite well.  Some do not.  Of course my preference against big and toothy is to be somewhere else.  Second choice is a 12 ga.  Neither the Rowland or 10mm are desirable but have the great advantage of always being with you.

I don't know. I would be a little leery of converting an old .45 1911 to .460 Roland. There is a heack of a lot of pressure difference between the two cartridges, and I would be wondering if a gun designed to handle the pressure of a .45 round could take that pressure increase.

Design is fine.

I would not use this in a pre-1921 1911 that may not have a full heat treat.  But I doubt many people would put a 460 Rowland upper on a frame that old.

Some of the early cast frames my be suspect too, but any modern 1911 frame is plenty strong.

Clark has a list of pistols that are strong enough and a list of ones that will not work.

When I ordered mine, they question you pretty thoroughly on what gun you are using as the base.