@Milmat
Hi, welcome to the community. Normally the different hardware versions of the same models could still be able to achieve the same network performance.
Since you already have Deco X60 V2, here are some comparisons with V3:
1. V2 uses Homecare and V3 starts having HomeShield. So if V3 is the main Deco, the Mesh Security system would be via HomeShield.
2. The latest firmware of X60 V3 1.2.2 has added some great features which are not available for V2 now but are planned to be added in the future.
3. "Test Internet Speed" on the Deco APP will be no longer available on Deco X60 V3.
Thank you very much.
Best regards.