I would be interested to hear from anyone who has any experience with this company as well as any build suggestions.
I assume you have already done so, but if not, you should talk with Creative Mobile Interiors (creativemobileinteriors.com) as many of us consider them the premier Sprinter converter in the country.
As far as build suggestions go, you may want to look at the build threads for the Sprinter expedition camper I had until recently:
http://www.travelvans.co.uk/id59.htm
Some of the things I did were clever and some weren't; let me know if you have any difference telling them apart.
BTW, I put the link to my build threads that goes through the Travel Vans site rather than the direct ExPo links so you can see about the Travel Vans book. It is one of the best overview resources available for someone starting out with the design of their own conversion. Depending on the experience you already have, you may find it to be worth the investment.
Good luck with your project.