Also,very cool linked site littlebig audio!

http://www.burton-manor.co.uk/ is interesting!!!! midhorns on the HF horn!!!!!!

Interesting choice of MOSFET for PA power amplifier,the on resistance of those things are abit higher,higher supply rails required-but simpler circuits! veroboard lol! take that Mr Bigbrand super amazing 5kw SMPS with 'DVSC PIL' and 'OPT' haha!

Regarding basshorns i think that your method of horn folding is good for those drivers that require small Vrc.For PROsound typical bigbox drivers-the old S style seems to often have a very useful rear chamber,that happens to be ~60litres etc which the driver wanted anyway haha

Regards
Mike.e