The comic had an article about one make series a few weeks ago featuring some of the above, a write up, and some info about costs and rewards on offer.
Sure one make racing might stifle technical development but there are plenty of series that don't.
It depends what floats ya boat, developing a bike very technically or developing the rider on allegedly equal machinery. Its nice to have a choice or do a bit of both.
In some respects it can be a mis conception that ome make stuff doesn't have technical challenges, getting the best from a bike within "tight" rules can be very technical and/or costly, can be even more costly developing one outside da rules, especially if the tech scrutes are on the ball
Ray.