I still have no idea what your system is all about, but my inclination is always to go with a web application of some sort when possible and there is very little on the end users side of things these days that can not be done with them (java / java script / whatever ). People understand web applications, and are not as afraid to use them. Less training, more future proofing, and removing the responsibility for security and such on the back-end from end user. Just all around more flexibility. The whole open source / whatever debate becomes irrelevant from the customers / client perspective. Ride the cloud dude (I want shoot the guy in the marketing department that came up with that

)!!!
Me, I am cheap skate. If I can not find an open source solution to it, I don't do it. We are an all linux / open source shop (including desktops), and I have just saved way too much time and money to ever look back. Our annual IT savings has got to be easily over $50,000 a year because of it. I think the only closed source technology we run is on our cell phones, and I am hoping to eliminate those useless dogs from the business sometime this year with the new generation of linux based phones.