I've had both.

The XRAY is essentially a B6.4 with expensive spare parts.

The B7 is a new design philosophy unlike any other car on the market. It's been successful so far.

I don't think either is "slower" or "faster". They drive differently, the B7 is a little smoother by nature. The B7 is easier to run (for me) because there is a much wider selection of option parts and spares availability is better.

Knowing the way that XRAY operate I would expect the XB2'25 to be a B7 copy.