I agree! Demos are waste of time and potentially money. There is so much that goes into setting up for personal preference. You can't achieve that in that in a short period of time.
There is always excitement for a new bike arrival, but then there is reality of - this is going to take some time to dial in. There are micro-muscle adjustments and muscle memory. Yes, you get to the 80% solution quickly its the remaining 20% that takes time and the most critical in determining if this bike works for you.
The newer geometry has been eye opening to me. I have always been stuck in smaller is better until recently. I got an Evil Offering. I love the longer geometry. However, I learned that I had bad riding habits that I developed on shorter geometry bikes. I realized on a short geometry, based on weight distributions, I could easily compensate with bad riding form. On the longer geometry, bad form shows its head very quickly. In practicing better form and technique, I realized that the size was a little less critical, but preferred the longer geometry. The longer geometry requires more focus, but that makes it a lot of fun because when you nail it - wow does it feel great!