[Gpa113]

Sounds like that was a particularly tricky introduction to running a Proxy event, well done for persevering Jeremy 

The following two stages will be my 4 lane permanent Scalextric Sport Track layout,  should suit the tarmac style cars, but will be good for all entries. 
My second stage is planned as SCX ice effect track, combined with Scalextric Sport Track, not the very old classic track. If I encounter the same sort of problems as Jeremy I will swop to a combination of Scalextric Sport and Ninco off road track, but without the obstacles,  obviously 

Regards the older Scalextric classic track we did try to incorporate two of  the wonderful Goodwood chicanes, fitted back-to-back,  on the 4 lane sport layout.  They proved to be a nightmare, simply because of the depth of the slot, which as Jason has noted is shallower than Sport track. 

My two entries both have Ninco sprung guides, and appeared to cope OK yesterday.  
It's tricky. You get a good variety of track pieces in the old classic track,  it's super cheap, gives good grip (especially for a rally event ) but it is very old, and really outdated.   I will try my SCX ice effect track stage, but have the option to change if necessary.