Earlier quoted context omitted.
I have had a series of bad experiences with Trinet. Not so bad that it's ruined my life, but bad like "I can't believe this is the best we can do for HR". I like the idea of outsourcing that sort of thing so we can focus on the hacking, but I feel like that particular space is ripe for disruption (to use a clichéd term).
A great company solving the "Back-office / operations" side of a startup, including HR and benefits management, is Advisor. http://Advsor.com Yeah, the website is being updated, but with clients like Uber, ZeroCater, PandoDaily, Buffer, Expensify, and 70+ more, they are a SOLID solution.
Based on your experience, how do they charge (per employee, per transaction, etc) and how much does it cost, roughly?