Personally I think PT's should be compulsory at National level. It makes life a whole lot simpler and would speed up the time in between rounds, making the day end a little sooner (especially Sunday). Most of the people at a National event have travelled a fair way to get there, getting home on the Sunday after is a nightmare at best so any time saved would be welcomed by all. I can't see why they would want to change to anything else that isn't compatible with the AMB.
Clubs purchasing anything else are surely alienating themselves and would struggle to get anyone apart from a few hard-core members to attend their meetings.
In the case of the Bedford club with the I-lap system, they are building an off-road track that would be really welcomed in the area as we need more tracks on the regional map but by running this system they would charge everyone who entered a couple of quid to rent one of their units to race there, or you could of course pay the £35 to race there once a year. It saves the club some initial money but it doesn't really save the user in the long run