I am polar opposite on this topic.
Many years ago, I was a Network Engineer who was given responsibility over a enterprise with a single 61c and several 11c's. I was told to learn the switch and begin using it. When I asked where the management interface was, I was shown MAT (which became OTM and currently TM). I noticed every time a made a change in MAT it would open a terminal window and process commands. After a month or so of watching MAT's terminal window process changes, I began to use the tty interface directly. I used MAT as a learning tool to program.
Today I still use TM regularly, but not to manage sets, I use the virtual terminal as I like how TM's virtual terminal helps with the programming.
There is a status bar that converts the nortel abbreviations to plain english on the fly.
You are allowed to use the backspace key, the commands don't actually process until you hit enter.
There is built in help buttons.
When an error occurs on the switch such as bug or sch, there is a single button you can push for explanation.
When you enter a LD through the virtual terminal, there is a button that will bring up the Software Input/Output for the LD you just entered.
In conclusion, TM's virtual terminal for maintance to me, is much more effecient. Procomm is better for bulk changes as it supports scripting.
TM is much more heavily used in my case than procomm, then again I'm a Telecom Admin for a large company, not an install tech for a vendor.