Sold all my Williams diesels a while back as they did not, for various reasons, fit what I was looking for. No problems with how they ran.
I do have several Williams brass steamers that have been upgraded to command. They look great and run well. My two scale Williams GG1s, still conventional, have been run a lot at shows and they have been great, pulling a 11 car pax train at speed.
I am looking at getting their scale FA-1 set and upgrade it to command. However, I need to buy two AA sets to get two powered engines plus find a B unit.