I'm a convert to the GP. But I wont dis the euro blade, as I think for every reason their is a season.
For more novice paddlers, a euro blade is easier to keep up to speed with a group. For more experienced paddlers, a GP will radically change your stroke from what one might be used to with a euro.
Once used to the GP, you realize you dont lose ANY real bracing power. You simply convert to using more skulling braces. Take yours out, and compare rolling with a euro and a greenland... no real difference... if anything the GP is much easier on the body.
I paddle around 100+ days a season, and often end up suffering repetative strain injuries by the end of it (with a euro blade), such as tendonitis in the wrists, and bursitis in the shoulder. This is even with a very low-angle stroke designed for touring. This last 100+ days with the greenland have caused me no pain. I feel better than I have for years.