The Pioneer Elite line is still around and they are still quite good. Really there is nothing wrong with your receiver and maybe you should keep using it. It's more of a convenience thing whether you should upgrade or not.
First off, do you have 7.1 speakers, or plan to add 2 extra speakers to your existing 5.1? If not, then that's one reason not to upgrade.
Now the biggest reason, as I said, is convenience. Most sources and displays nowadays have HDMI and that is definitely the way to get the best signal from your source to your display. Second to that is component video. Those are the only two cables which can carry HD signals, and that looks to be the weakest link of your VSX-07TX: it only has S-video, no component. So it depends on the number of HD sources that you have: if only a couple, probably you can plug them all in to your TV and switch sources on the TV, and have the audio run separately to the receiver. If you have a lot of HD sources, you could buy an external HDMI switcher or something along those lines. So you will have to switch sources in two places: switch the audio in the receiver, and the video in the TV or external switcher. So that is the loss in convenience in not having HDMI in your receiver.
Now, your receiver also lacks DTS processing. IMO this is not a big deal, but some people would disagree.
But really, that's it. Personally I upgraded to an HDMI-equipped receiver because I have several HDMI sources and did not want to mess with switching the TV. But if you only watch one source most of the time, then that would not be a big deal.