My experience with the epic narratives, or rather lack thereof, can be grouped into the following categories:
1. There is epic stuff happening, but we play little people who cover in fear of it all.
2. 'Sure, you will get epic stuff, but start small'; 30-50 weeks and about 30 sessions later, the campaign dies, never reaching the epicness promised.
3. 'You are big damn heroes!'; cue opposition being about the same level, de facto making the 'heroes' pretty average in the setting.