At our company the rep gets a one time "bonus" for selling service agreements. More commonly viewed as being penalized for not selling service. However, I understand why.
We don't truly believe you are our customer if you don't have a service agreement. Without service, you are more apt to be dissatisfied with your product and unless cycled regularly by your sales rep will become orphaned and be lost to the competition when you are ready to upgrade.
I believe the problem is any time we take money from one place, it leaves a void or has to be made up somewhere else. Perhaps, as v-tec stated, a better way to add income is from software solutions. Or, selling network/software support agreements for connected products which allow the customer to purchase blocks of time in case they have a connectivity issue or upgrade their computers and need to install print drivers/scan folders, etc...
I'm in sales, but I don't think it's necessary to compensate on a residual basis for service.
I believe this will remove the drive from the sales reps and they will become stagnant, getting fat off of the work they have done in the past.
We have a contact quota/goal at our company too, 100 per week. Although I don't always remain as disciplined as I should I still believe the key to success in selling is the number of contacts made. Product knowledge, presentation, attitude, etc... are crucial, but unfortunatelly, they still come second to contacts. It's humbling and I kid myself sometimes because it's a lot easier to focus on the others because there is no rejection involved.
I used to do most of our connectivity, but now we have someone else who can devote more time to this so that I can call on prospects. The knowledge I have gained from learning the connectivity has paid 10 fold in my ability to sell with confidence and create new solutions for the prospect. The clicks I have captured by adding printing and scanning have solidified my customer loyalty and positioned me more as a consultant than a copier salesman.
I think we need to always be aware of the opportunity to capture clicks, but I think tying them to a pay incentive to the rep is not necessary. I want my service team to be the most professional and highest paid guys in their field. One of our sayings is that "the salesman sells the first copier and service sells the rest".