There's a lot of crowing about "the spirit of the 60's" but what about the spirit of innovation? I thought that the reason scratch-building was such a trumpeted concept was because of the desire to prove the merit of each builder's own design? Just out build the mass-produced piece.
Let me preface this by saying this is my response and do not take it as that of the board's.
Just take one look at the chassis built by Tony P, Steube, Samson, Bruce, Warmack, Anderson, Gorksi and many others and you will see lots of innovation that is still within the spirit of the scratchbuilt chassis on which retro racing was founded. Snap together kits with pillow blocks require nothing except a soldering iron. Real scratchbuilding requires at least a dremel too. Some can be built without a jig but it helps.
The Warmack and JK "kits" come with pieces that can allow one to make a chassis in the true spirit of what retro racing was about. R-Geo's kits affordyou the same opportunity. Some may argue that the bent up front ends are no different than pillow blocks. To me, they are quite different. Some of the early chassis built in D3 that got us all started had these and they were hand bent. Some may say well a separate 3 piece bracket was allowed before. Well, it really wasn't as the bracket was made in 3 pieces but sold as one unit and put together by the maker. It's a mute point as they are no longer made.
While looking at the classes of chassis for ideas that you mentioned is useful, it does not mean that making a copy of those is what was intended for or would be allowed in this type of racing.
Everyone is free to buy what they want and build what they want. I'll probably get one of those S7 chassis to play with for some regular old slot racing fun. I just won't use it in retro racing. Retro racing is not about growing the designs where we replicate the history of slot racing, it's about replicating the spirit of scratchbuilding and the cars of the times.
As has been said by many others, the FX and S7 will find a home perhaps in another class, or in another organization. People will buy them and make cars from them. They will buy parts. It's all good for slot racing and no different than those that buy other types of slot cars and parts.
Some may think retro is stifling. Well, not to me or the many guys that come to run these wonderful cars, get together with friends and have a good time.