Good call, I suspect you'll find either does a fine job.@KEW
Thank you for your post. Today I bought two second hand AVRs: Yamaha RX-V1200 and Yamaha RX-V659.
I'm going to see how they do and then decide which one to keep.
I would recommend adding a sub when funds allow ... both from the perspective of filling out the bass and unloading the demand from the 4" drivers.
However, the stock Pioneer is probably the best sound available at the price and the same can be said about them after Dennis mods them.
Happily either of the AVR's you are considering will do a fine job of High Passing the mains when you add a sub, so it will be an easy upgrade when the time comes.
Also, I guess I should note that the budget subs I recommended are not really subwoofers at all. I call them subs because that is what the market calls them (they also call it a subwoofer when they add a 4" "subwoofer" to 2" speakers for a PC speaker system). The reality is that for a budget "subwoofer", you are ideally getting a good woofer module aka "mid-bass-module" to fill out the mainstream music bass which goes down to the mid-30Hz region. Less than ideal, you are getting a crappy bass module that either attempts to play too low and/or is tuned to output high SPL at the port tuning frequency with no attention to maintaining linear frequency response resulting in boomy bass. You can actually get away with this strictly for Home Theater (not music) because we generally don't have any memory of the accurate sound of a dinosaur stomp and the added SPL is simply fun! However, it can ruin music!
On this count, when/if you can afford it, I can comfortably recommend the Dayton Audio SUB1200 ($150 shipped). They do a great job of filling out the bass in a linear fashion, but even when you hook them up in a HT for LFE they do not embarrass themselves. They won't reproduce the 20Hz content, but they have well designed limiters to avoid mechanical slapping sounds, etc. I set my GF up with a pair of the SUB1200's and played the introduction of "Live, Die, Repeat" on them (a strong 16Hz signal) and they certainly do not sound like my dual Outlaw X-13 Ultras, but they made some impressive rumble without shitting all over themselves and I consider that ability to cope with an "overload" situation the mark of a very well designed sub (or mid bass module) given the price of $150 (shipped)!
Good luck with your audio journey, and, most importantly, enjoy the music!