Had a quick go on my new Q3, and compared it with my Quest Pro.
I don't think passthrough is hugely better than the Pro, at least not for practical usage. It is definitely better but not orders of magnitude.You can tell theres some extra processing going on, as initially when you look at something it looks blurry then it's sharper a moment later.
The room scanning and the depth sensor make room setup really easy. Wish that sensor hadn't been deleted from the Pro!
The colours are better than I expected. They are a little washed out compared to Quest Pro, but the black levels are about the same as the Pro without local dimming enabled.
The resolution bump in native games is nice. Good to have fairly sharp graphics, though you can tell it's still not native res.
The WiFi seems way quicker - downloaded and installed Asgard's Wrath and a bunch of other games very quickly.
The controllers feel like cheap toys compared to the Pro controllers, but the tracking feels very solid.
Will give it a longer play later as it ran out of charge very quickly. I'm going to need to dig out a power bank for the halo headstrap I bought for it.
Since you have both, are you likely to get rid of the pro or use it even less?
I have the pro and currently contemplating buying the Q3 so wondering if its really worth it or just stick with the pro