Cambridge 302 & PDA -- Value of adding Cambridge 303?

I'm planning a panel for a new Ventus, planning to get a Cambridge 302
and a PDA. My question is to what extent also getting a Cambridge 303
(nav display) is worth the panel space and cost.

I recognize that a PDA can provide almost everything the 303 can do
and more, except for maybe better headwind/tailwind. So it seems 303
would be mostly for 1) backup in case PDA fails, 2) ability to show
navigation to two TP's at once (one via PDA, one via 303).

I've heard that many competition pilots who fly with a 302 and a PDA
also have a 303. I'm interested in feedback from anyone who flies with
this configuration -- what are your main reasons for having the 303,
and do you use the 303 regularly in cross country/competition
flights?

Thanks,
- Frank