I think the pro ride route is the same as the 100, so hopefully we get the same benefit of road assessment and repair.
The organisers emailed me back today and said they have been assured by Essex council that all loose gravel will be swept up on the resurfaced A414. Even so, if it's a hot day and the tar melts then gravel is going to stick to tyres and, in my case, may get jammed between the back wheel and the cut-away on the seat tube - only a few mm clearance.