My personal experience is that tubular track, including O22-style postwar 31" diameter switches, etc., is bumpy. Rolling stock "clomps" through them, you can see the trucks bouncing and pronounced movement of locomotive boilers, etc. I never built a tubular layout with a 45-degree crossing so I can't speak about that piece specifically. But I've used both Ross and Atlas track, and find their switches and crossings MUCH smoother. I'll never build another layout with tubular if I can help it!
There are two issues- one is mechanical bouncing or snagging because the wheels fall into a gap in the rails. The second one is loss of electrical continuity, causing the loco to hesitate or even stop if it's going slow enough. Sometimes both of these issues happen at the same time. For example, a wheel or pickup roller falls into a gap, creaing both a mechanical snag AND loss of power. If it's just a loss of power that can often be addressed by adding ground wires, extra rollers, a tether to the tender or a trailing car.
A lot of people grew up with O22 switches and will defend them to the death. I guess they're ok for some things. But for my $.02, if you really want smooth operation, save your money for a newer track system.