As I understand it, you have some inquiries related to dynamic reconfiguration of the A10 GX XCVR. For your information, there should be no issue to switch between two different serial clock frequencies from two TX PLLs. In your Native PHY, you can specify "Number of TX PLL clock inputs per channel" = 2. Then use dynamic reconfiguration to switch between the two TX PLLs. Please let me know if you have any issue configuring this.
Please let me know if there is any concern. Thank you.