Generally if strict QoS control is required in a WAN/MAN environment I would recommend 'real' routers (2800, 3700 etc). The reason being is you can apply ingress & egress QoS policies to strictly control the traffic and ensure SLA's are adhered to etc. Ethernet WAN services are now cheaply available so most customers get 10 or 100Mbps LES circuits instead of traditional WAN links (like 2Mbps E1 links etc). Since a LAN switch will inevitably be purchased to support LAN clients many customers want to simply terminate the Ethernet WAN onto the switch (typically a 3560 or 3750) to avoid the additional cost of a router. Even with the IP Base image on a Catalyst 3560 we can route over a LES circuit,the 3560 effectively being a 'router'. Generally this is fine as we can strictly queue any VoIP using the strict-priority queue, however if anything more 'clever' is required we are a bit stuck since this platform doesn't support egress QoS policies; just queueing based on DSCP or CoS.
If anything more clever is required a 'real' router will do the trick and I would generally recommend this option. Unfortunately even a 2800 will struggle with a 10Mbps link that was highly utilised (if it was hit with lots of small packets). A Catalyst 3560 would easily cope with this traffic though? Which has caused a bit of a dilema.
I hope I have explained the dilema and am after other peoples solutions/ideas.