I am a bit confused...
How many DVDs do you typically watch a week? What kind of movies do you like? How many movies do you own? How often do you rent?
If you own a ton of DVDs and really care about the upconversion of those discs, then the Oppo Digital is one of the best on the market for this end goal and at the price.
If you don't own a lot of movies, then I would have to wonder why would would say that you won't be renting on Blu-ray - especially with a front proejctor. The difference I see between upconverted DVD and Blu-ray on my projector is significant, and immediately noticable.
If your projector is a PT-AX100U projector, from Panasonic, then you would be best sending a 720p source to it (not 1080p) as that is the native resolution of the projector, and will produce the best results typically. Since DVD is 480i, you are definitely missing out when you don't take advantage of the best source.
But, a large DVD collection begs for a quality upconverting DVD player, and the Panasonic is not going to deliver the best in quality for upconversion.
But, the average Blu-ray is going to blow the pants off the best DVDs for quality - especially on a 100"+ screen with front projection.