having just replaced the blade seal and cleaned up our china bowl Thetford Aurora (2 pedal) Im not sure i would want a more complicate Thetford Techma - all I've every heard about macerators is that they clog w/ nasty debris (hair/paper etc). I subscribe to the "less moving parts" means theres less to fail theory.
I just looked at a
https://www.youtube.com/watch?v=vQ5x4OURmNk on that Techma - holy cow that thing is complicated & has tons of narrowing passages and hoses...NO THANKS !
Ive never had an issue w/ our black tank - I thoroughly rinse it clean after every trip.
Id stick w/ Thetford their parts, seals & rebuild kits are plentiful !
while i had ours off the floor i took the opportunity to add the $23 riser kit