I've just gone from 15s to 17s on my EF at one of the tyre/wheel shops here in Newcastle. They use the adapter hubs (not spacers) and have done quite a lot of them on E-series Falcons. As you've probably found, there's bugger-all wheels that actually fit E-series, whether Tickford copies or otherwise. That's the reason I went for the adaptors.
As they actually bolt to the hubs, they shouldn't place anywhere near the anount of stress on the studs that spacers do. Btw, the adapters were $300 for a set of 4.
Red ones go faster.....