As a Power Tap owner who thinks the PT actually works, I do fail to see the real need for PM's that install in BBs, are limited to one bicycle, and run in the $3K range. For most amateur racers, the PT works. Worked for Floyd Landis too (he had a PT on his bike during his now infamous Tour de France failed doping test breakaway performance). I get the advantages, but to me they seem offset by the high price and the disadvantages. To each his own.

At a minimum I'd suggest a PT as a first PM, with an SRM or Quarq later.