I am well aware of the Edge Hill crossing operations for any freight (and any ECS too), I've been around along time and know what issues it creates. There was a period in time, you could note the difference in which signalman was on at Edge Hill SB, the more experience persons clearly knew when the best time to slot a train in to cross all lines, especially if it was out of path. As for not signing the road, well no one has, given how long it has been out of operation but I'm sure that will be overcome in due course when its 'recommisioned' as such.
When I was referring to easier access for turning on a triangle, certainly referring to rail tours and such like as Speke would be the easier option. Even with a big traffic flow, any reinstatement of bridges / lines in the Edge Hill area, most of the land has gone anyway due to the relevant 'business park' now in situation, so I would agree with you, that would never happen. However. I would never dismiss any 'F/L' traffic coming back from the Docks which may need to call in at Garston FLT once again, although the ecomonics would suggest go via Earlestown to and from Crewe as a complete train (there are numerous road containers travelling from the Docks to Garston and Ditton, only need to look on the M57/A5300, let alone any those trucks that take the route via the Pier Head).
As for whether it was F/L Class 47 that cause the issue, Mark may be able to confirm in due course but Freightliner were using the Class 47's upto 2006 and they were still calling at Garston FLT to / from the Docks around that time. Certainly not beyond 2007 as F/L withdrew from the Seaforth CT service (which went direct to Crewe BH via Edge Hill Wapping) in 2008.
