another difference is with a power off 180 you are usually landing with a headwind.... where a "teardrop" is usually a tailwind...also the power-off 180 isn't that tight of a bank like a "teardrop would be"... @ 500-700ft that would have to be a +45 degree bank.

all in all I guess it would depend on the airplane and how much energy is lost (Cd, Cl, weight per bank, etc)... maybe usmc-sgt's highlander would be able to do something like that...

however most pilot error/aerodynamic accidents happen when bank is introduced