Your variable comp model can't be just a straight % commission, or else your sales reps will go chase enormous contracts that may be bad for your company. If you want to target smaller deals, weight their comp more on number of deals closed. There are hundreds of metrics you can use to judge your sales staff, and getting it right is hard. Your sales strategy needs to be driven by your business strategy, which should decided upon at the highest levels of the organization.
There is an art to creating variable comp models. You need your metrics to line up with your strategy. A star will deliver the numbers no matter what they are; while a low performer won't. The model is proven, but the details are up to every company.
It's not 'proof' by any stretch, but I was recalling this article while typing the original comment: http://www.saastr.com/a-framework-and-some-ideas-for-your-fi...
I don't entirely recommend this book, because I feel that its arguments are not as well supported as they should be, but it is at least an interesting scan: http://www.goodreads.com/book/show/541132.Punished_by_Reward...
Just to give you an idea of why this model is attractive ... and also why there is such huge churn in Sales. If you don't succeed pretty quickly, you're going to be broke.
What makes the rockstar saleperson's commission so much happier spending compared to the rockstar engineer's salary? I think simply the ability to measure the ROI on those dollars. The day anyone figures out how to directly measure ROI of engineering dollars with the same "obviousness" as sales quotas / commissions, it would completely change how we hire and retain engineers.
I'm interested in hearing how this is proven. I've seen incentivized sales reps close deals that damaged the company, just like I've seen "successful" marketing campaigns that eventually killed their products.
If you use bookings as your metric for bonuses and then turn around and use bookings to measure whether the incentives are working on a per-worker basis, you'll miss a lot of negative effects. If sales starts overpromising the product, sabotaging each others' deals, or even chasing after bigger but short-term customers, you could see the metrics improve as the company falls apart. And then there's the fact that, even within a department, you'll hopefully have a group of people with diverse motivations.
That's why I'm curious about how this model has been "proven".