I've seen quite a few posts on here mention that speed dial is more efficient. Regardless of whether you think it is or not whilst driving or cycling you would need a cradle to effectively manage this unless you hold the phone in your hand. As this is illegal in an increasing number of countries this ought really to be addressed at some point to allow the phone to be used.

First option would be a decent cradle and a selection of speed dials. As you would have to look at the screen for this it's a tad less safe IMHO.

Second option allows S60 style functionality via established bluetooth protocols. I know some people have had issues with S60 dialing but most people I know it generally works for. If not then training function?