ADS-B or just Mode S for class E airspace?

PowerFLARM PCAS sees mode C and S transponders, as badly as Ramy describes. PowerFLARM does not see UAT direct and cannot decode ADS-R or TIS-B messages, so you will not see that traffic even if you have ADS-B Out to make your glider a client for ADS-R and TIS-B ground based services.

Future products from FLARM OEMs may improve that, but the story there seems much more of a mess than I hoped it would be. Maybe more on that later, elsewhere on r.a.s.

If you want to see all that stuff today you need a separate receiver and display like one of the GA oriented EFB applications, like ForeFlight on an iPad or iPhone.

But... having ADS-B Out is a big step... it makes your glider visible to all those GA aircraft in lots of situations... many folks who have ADS-B In today have dual-link receivers that will see you regardless of whether they have ADS-B Out or are within TIS-B service coverage.