I think timing tells are generally over-rated. So many people who play online are playing multiple tables, and how do you know if a delayed action is because a player is thinking about what to do, or if he is playing hands on twelve other tables at the time. Similarly a very fast action might be because he doesn"t have time to think about his decision as he has action going on elsewhere.
The only real tells I base decisions on online are around bet sizing and historic action (if I have notes on a player, but my note taking is generally poor because I"m playing too many tables).
For me the HUD is an essential tool - without it, it"s like driving round a blind corner on a foggy night, with no lights on the car...... and you can bet your bottom dollar that most of the folk you are up against are using a HUD against you, which means they can drive that same corner with fog lights on, GPS, and radar tracking!