I generally use 3-4 MT engines when translating, but I've found that depending on the type of the text one engine may be more reliable than others.
The problem is that in the TR window you can't see which engine the results come from unless you click on them individually. Then at the bottom of the pane, the name of the engine appears.
I think it would be much more convenient, if the name of the engine (could be shortened) appeared right next to the results for us to be able to identify them immediately.