About K2 I fully agree ... it's waste of time, if you are using J3.4 - it only slow your down - now in J3.4 times default articles have so many nice features then there are two exceptions, when you might need K2:
1) You too lazy to install comments component.
2) You need custom fields (also for lazy ones).
About K2 v3 they promised to be ... 2 months ago and ?? nothing changed.
---
About VM - if you speed at least 5 min on VM official forum you will see how many "stupid" errors users gets during normal use,
it's madness what they did with this software.
All my Joomla friends since 2-3 years use only HikaShop for private/commercial projects.
Even those who used only VM in past. I want to be honest with you.