We once used a 172XP think 195hp and it was as good as C182 except
less fuel. Re the C150 in Australia there are several C150 with 180hp
and they climb out better than PA25-235 but have to level out at top
of tow a little more than pawnee and thus overall tow time ground to
ground would be similar pawnee. The longest operator in Australia
would be Kingaroy Soaring Club and contact Neil Dunn for more info
(find on google). I do know prior to C150-180 Barry Deeth did a
C150-150 but think it got damaged in storm before it did towing. Think
the 180 hp would be the way to go. Ian McPhee Box 657 Byron Bay 2481
Australia +61 2 66847642