In reply to Stefan Kruger:
> Two whole tech grades to spare is rather a lot.
Your profile suggests you may have rather more than that in hand, unless it's not up to date.
I do agree with your conservative approach comment though and I think that's the reason for the two tech grades being a reasonable approach for many people in their early years leading.
I have on-sighted sports routes (particularly slabby ones) absolutely right at my limit. I have found that very valuable to my trad climbing. I'm not sure what's wrong with trying to on-sight sports routes if you are into trad. I found it helps me learn what I can do on-sight, rather than what I *think* I can manage when on trad. It's not exactly the same approach of course (ie. you don't need all the same tactics and you are free to climb). I do train at the wall incidentally so it's not as though I don't effectively do some redpointing, albeit indoors.
Someone commented that this was a bit of a self serving thread. It wasn't supposed to be, genuinely. I am interested in this and I suspect a lot of other people are too. I'm not trying to say there is a right approach to grade differentials, just that what I was once told had pretty much worked for me over a period of time and averaging things out. Yet I am sure some people do have a completely different experience.
>
> Sport climbing 'properly' - as opposed to treating sport routes just like trad routes with fixed pro - has really opened my eyes, and my grade sky-rocketed (for me) as a consequence. Adding some sport climbing and especially bouldering into your mix will seriously benefit your trad ability (unless you get hooked on the dark side completely ), and you should be able to squeeze that differential.