Can't speak for the Pioneer but surely the Yamaha DSP-A1 is well worth the money and should be available for much less then GBP1000, at least I would not pay that price now.
Okay, so it's "old" now (replaced with the DSP-AX1) but to me it sounds damnd good in AV and stereo is ok to me, too, but perhaps I am not that demanding on the stereo-side of things, rather a casual listener than an audiophile.
The A1 has most features you will ever need, certainly enough in- and outputs and lot's of power, even though it's not THX certified I strongly believe it delivers as promised in the specs.
I leave it up to you to count the DSP modes as a plus or minus, a matter of personal taste.
However, you may want to compare the A1 to some newer AV amps/receivers like Denon AVR-3300, AVR-3801 and AVC-10SE and surely they are some of other brands which might offer an alternative.
But in the end you must decide if it sounds good and if it's worth the money to you, some of the budget amps do offer a good to excellent performance, too.
Don't forget to audition with movies AND music, usually AV amps are better in the AV department (since they are built for that in the first place).