The Monitor Audio PL100's should certainly be on your shortlist, and do also try the ProAc Response D2's.
If you can find some used or B stock, give the KEF Reference 201/2's a spin. When I tried the combo I felt the 909 did an excellent job driving them, even with the 4ohm load and low sensitivity - but then that's always been a strong point of the 909.
Not my cup of tea with Quad amplification, but you could also look at the ATC SCM19's, which, along with the 201/2's, will have a placement advantage over the other models due to their sealed cabinet (the 201/2's are ported upwards, and act like a sealed cabinet as far as placing is concerned).
The upcoming B&W PM1 might be worth considering too, as it uses much of the technology they use in their 800 series.
If you do go for any demos, make sure you hear any possible candidates with the same Quad amplification - otherwise, any results from auditions with different amplification aren't going to be of any use to you.