speaking if jvc, i also built a plinth for a jvc ql-5, added a black widow arm and a soundsmith cartridge. i still prefer the sp25, but that is probably the arm/cartridge combo making the difference. it's hard to compare tables since it's rarely apples to apples comparisons, there are way too many variables.
also, on the mat subject, i added a carbon fibre donut to the rubber mat on the technics. blacker backgrounds than the rubber mat alone.
the jvc is definately a nice solid table. the platter is heavier than the sp25. there's a pic of my table at:
http://www.canuckaudiomart.com/details/180794-unique_turntable_jvc_ql5_direct_drive_in_custom_plinth/