http://niac.usra.edu/studies/9801/9801Final/McNuttFinal.pdf was written in parallel with Winglee's research & therefore doesn't include M2P2 in its calculations; but doesn't crunch some useful numbers for nearterm interstellar missions. Oddly, it identifies Alpha Centauri as a harder target to reach that somewhere like Epsilon Eridani (although the mission to EE would take considerably long)... the reason: the cheapest was to get velocity is still Jovian/Solar gravity assist; & orbital configurations for an Alpha Centauri flight are rather harder than for some other targets. If i've read the M2P2 data correctly - never guaranteed - the system avoids some of the problems identified by McNutt; but not all of them....