17:48In 2020 HK has upgraded the VP9 from 15 rounds to 17 rounds. Thus greatly advancing in my Rounds (or kinetic energy) per Size & Weight  9mm Pistol spreadsheet.  The top Ambidextral Pistol for "optimal use of cover".
.67 rounds per ounce
15:19Ambidextral Gunfighter review of the HK VP9.  A solid alternative to the PPQ, if the right side slide release works..59 rounds per ounce
29:45A neck 'n neck battle between two 15 round, 9mm pistols. 
VP9Best Paddle Magazine ReleaseExceptional TriggerBest grip feelAdequate left hand slide release
PPQExceptional TriggerBest Trigger resetBest ambi slide releaseLightest

Without a doubt the best training aid for pistols (and beneficial for rifles, too) MantisX

4:56HK VP9 right side (left handed) slide release disapoints.
Because gun shot trauma all require the same emergency response whether from 22LR, 9mm, or 45ACP.