#1 - the person at the dealer who does oil changes is usually the LEAST experienced mechanic in the place, or perhaps the "slowest". And remember that most these mechanics are not exactly rocket scientists. While there will be some experienced and well trained repair people at a good dealership, there will be few college grads or mechanical engineers working there. While I do honor these folks, and I worked with aircraft mechanics and avionic technicians for a few years, I do recognize their limitations. So if it's a job you can do yourself, and IF you feel you are mechanically competant, chance are you'll do a better job on service items that you can do.
#2 - the Fumoto valve is available at somewhat lower prices from other source than Fumoto, which sells at list price. Try Lubespecialist.com - he shipped me mine the same day and I saved about $5.