This is an interesting observation. I think we all were of the opinion that "HPL" was really a "H" without the rubber magnet protection. In reality the JBL rubber protector does have magical magnetic capabilities.
I have had a 2035HPL on the shelf for some time and wanted to find out what I can do with it. Turns out that I was lucky as the 2035H has an Fs=48Hz / VAS=140,5 but the 2035HPL has an Fs=43Hz and a VAS=6,8.
That should provide for good bass in a small cabinet. Maybe even bookshelf size. :-)
http://www.jblproservice.com/pdf/Thiele%20Small%20Parameters/Theile%20Parameters.pdf
Kind regards
//Rob