I used Droid 1 for more than a year. Droid 1 was excellent at that time but suffering from small internal storage and memory. Due to very small available memory, Android OS needs to flush periodically to load new application. With 256MB memory it wasn't easy and Android OS wasn't very good at that either. So, there were lots of devs working to make Droid 1 usable device.
You might not know how bad it was. I was in Costco one day and got a call. I wanted to answer but my phone was frozen for a few min and missed call. it ran very very very slowly. I dialed to caller and phone didn't respond. After paying, I pushed my cart and moved things to trunk and went to gas station. Then my phone finally dialed. I cancelled it but there were so many call since I pressed many times.
After eclair, it was better and Froyo definitely helped. Internal storage was problem but luckily I am good at Unix. So, I modified boot script to change a few directory permission and used cache partition for data storage. No other way to use the phone since program space was so small. So, rooting and modding is sort of mandatory business.
With D2G, I am stick to Stock ROM. Not because I am scared of modding or do not know how. I know how to create ROM image and modify so, if I need to, I will. But D2G has much memory and big internal space. After installing all necessary apps, I still have 6GB left. with Droid 1, I always worried about space and kept deleting email. Now, that's the past. I don't also worry about background process since I always have at least 140MB left. Compared to 10 or 20MB with Droid 1, it's day and night difference.
I don't think modding is critical for D2G. Just my 2 cents.