What one needs to realize about the crux is that it is not a comfort bike. It's for racing and so the geometry is for racing. Also the E5 alu model is really really stiff. Not sure about the zertz inserts.

If you want to get the crux on the road you need road tires. Not a problem. If you want to use the roubaix for gravel grinding it's not going to be optimal. GG is a thing nowdays so you might get into it.

About the whole one bike is faster than the other... well, they are different but none of the differences directly affect speed. Except of course the front chainring size on downhills. If you are a beginner you are most likely not going to spin out the 46/11 on flat. Then again the crux has a compact so you can just swap the chainrings to bigger if you feel like it.

Handling geometry is preference and if you are a beginner, well then you just don't know yet what you like. It might go both ways. The twichier roubaix or the more stable at speed crux.

Also the tricross and crux have different geometries. I can well understand that the tricross lacks fast handling but the crux is very snappy indeed when it needs to be.