Yes, just my C7s as APs with the RPI4 doing all the heavy lifting. Not using any dedicated switch for the Pi, just the C7's included 5 port gigabit switches. Once you set up the VLANs as required for your needs and a trunk port on each C7 to link it all up, it all works seamlessly.
They make for great APs. Never had a problem with them. Both are overclocked to 1GHz on the CPU, with heatsinks, for a little more grunt. I'm currently on a 50/50mbps FTTH connection, could upgrade to the 300/300mbps service next. We'll see.
For sure these faster connections have outgrown what the single core MIPS CPU in these devices can do if you want all the bells and whistles (SQM...), it was time for an upgrade.
Love the RPI4, couldn't get one until now, but sure had a few ideas pop up in my mind back when it was released and made a thread about it 
The Pi4 would love some WiFi 6 APs though. Doesn't break a sweat handling a gigabit connection... SQM or not, encryption or not, it doesn't care. Doesn't need offloading of any kind. Powerful little thing. You had to go x86 at higher power for such feats.