Sprinters for SNG
First generation Sprinters were a nightmare. The suspensions were topped out driving off the lots with all the gear. The drive train also suffered mightily by never deadheading. Transmissions, turbos, tires were automatic maintenance nightmares. Most of the glaring shortcomings were addressed very well and now the Sprinter is pretty much the standard.
Its all in the integration and gear. Some of the Sprinters are all the equal of most big trucks except for the work space and stowage.
Be wary if getting a used chasis.
The biggest problem with not having an external box is likely having you're chasis wear out before your dish/mast/operations gear does. That said if we were to replace our sat trucks today, Sprinters would be the leading chasis candidate.
Depending on who will do your integration, look at their recent deliveries list. Talk to operators of their trucks. They will know what details to sweat at the build. It will save many headaches down the road.
Omar