The traffic is at least twice as bad as you remember it. In other words, the San Diego you remember living in no longer exists. I'm talking hour long commutes to traverse 6 miles.
The problem with bicycling in San Diego is geographic more than infrastructure. If you live and work in the same area, usually bicycling is fine. But the entire city and surrounding areas are segmented off by large mesas, hills, and mountains, with the connections between the areas mostly done by freeway or 50+ mph access roads. So if you live and work in Mira Mesa, fine. If you live and work in Clairemont, fine. But if you live in Clairemont and work in Mira Mesa, forget it.
San Diego is what I miss the most. Yes, it is crazy-expensive to live there. Dollars well spent as far as I'm concerned. Some day I will return.