Can't compare because we used the GCH entrance twice on our trip. We just returned home yesterday. We got there 30-40 minutes before EE opening (depending on the day) and it was fine. In fact, during the 30 minute time (with a later EE start) we were closer and we got onto RSR first!
However, the line in GCH grows faster with each passing minute. Literally within 5 minutes the line grew by several people and families so every minute counts - but this was based on our experience during the days we were there.
We also selected the cast member that was the fastest in getting people through. During our last DCA EE, we got by several people because our line into the Park was faster. It's a generalization but some of the elderly cast members are quite slow in getting people through - but I do like how Disney employs them. Also, I quickly scanned the lines for the most high-maintenance visitors (e.g., several kids, slow people [for whatever reason], etc.) and avoided that line. Of course, even with all of this, you can still get the slowest line. LUCK helps
If your goal is to get to RSR faster, getting to the front of the rope drop to the right helps too. But if you are close to the front, your wait is never that long.
Good luck!