The answer to your question is something that no one else can tell you. It is entirely subjective. Some people find the quality of the blu ray videos to be far superior to dvds…others find it only a small step above upscaled dvd video.
Since you have a Blu-ray player, rent a good example of a Blu-ray movie and see for yourself. I would advise [I]The Fall[/I], or [I]Blade Runner[/I] or [I]Serenity[/I] from personal experience as examples of high quality video.
It is possible to back up blu ray movies that you own to single or double layer dvds, or to compress a large blu ray movie slightly less and burn to 25gb BDR or BD-RE disks. For that process you’ll need AnyDVD HD and a free program called BD Rebuilder. You’ll also need a fast computer, a blu ray drive, a lot of hard drive space and some patience.
The output from BD Rebuilder is astoundingly good on 25gb disks, and virtually impossible to tell the difference from the original. Compressing to DL dvds, it is still excellent, and clearly better than dvds of the same movie, in my opinion (I’ve compared).
Prices on BD media are currently depressing. The best buys I’ve found have been on ebay, but you should be careful of some dealers on ebay. In specific, avoid those who repackage BD media to save on shipping costs. I recently found a deal for 25gb BD-RE disks for $2 each on ebay. At that price, it is worthwhile.