"Upconverting" is the biggest bullshit "marketing term" ever come up with, or at the very least most misunderstood.
A DVD only contains so much infromation and that information is only enough to creat the (420?) resolution the format is capable of. If the DVD contained enough information to "upconvert" that resolution to the 1080 of Blu-Ray why wouldn't the DVD simply be that?!
All "upconverting" means is that the player can take that, compatative small, resolution and blow it up, as flawlessly as possible, to fill your screen. Without "upconverting" your DVDs playing on your TV through your BD player would be a box far smaller than your TV.
Upconverting does not make the picture better!
As for the time issue, the DVDs and BDs I play on my PS3 have no notable lag to hem when loading, chapter selecting or menu selecting.
The BD format has the advantage
of being able to play the previous format. This is a plus. It's like when people in the early part of this decade had to buy those VHS/DVD combo units to still play their tapes. Only a BD player is less bulky and cumbersome to take advanatage of in this respect. Any BD player, ever,will play DVDs. So buying a BD player doesn't "force" you to have to upgrade the movie collection too, like DVD did, unless you simply want the better qaulity.