FYI, Pioneer does not authorize any dealers to sell their Elite products online. If you buy from an online retailer you are not protected by the manufacturers warranty. I suspect there are ways around this.
I was not comfortable doing this, besides BestBuy have the VSX-21 for $599 last time I was there, it sounded identical to the VSX-23. A lot AVR for the money. I was not sold on the sound though. Just my opinion. Love the look of the Pioneers.
I ended up with the Denon 1910. Only downside for me is it's lack of pre-outs if I ever wanted to add an amp. It sounds really good though.
The Onkyo 607 is a good AVR also, (I auditioned most brands in this price range), check out some threads on how hot it gets. My cabinet is enclosed so that put me off a bit.
Figure out if you need pre-outs first and what other features are important to you, then audition the ones you like.