Bob- I've done 2 ERR upgrades (diesels), and fitting everything under the shell is the first challenge. Gunrunner John has been a huge help. A steamer is in my future...just don't know when yet. 
From what I've read, the upgrade of an MTH engine is straight forward when staying with MTH components. Switching to ERR requires additional parts, wiring, etc. The couplers are first thing that needs to be changed. I've also heard that the PS3 kits are not available but I could be wrong.
The ERR kits are easy to install as well, I've done LED upgrades on both which took more time and effort since I was upgrading conventional engines.
I have a few PS1's that I would like to do one day as well.
If the "scope" you refer to is the "scope of work", its as discussed. If you are talking about an oscilloscope then you're outside my learning curve too.
Good luck,
Bob
