Can't you make a decision before you begin about how hard you go and stick to it? If you know you're going hard then at least both of you are ready for it. If you start off light and ramp it up unexpectedly then it's a little dangerous don't you think? Sparring light but fast can still be challenging.

Even in light sparring there will always be the occasional punch which is more fluent or timed that little better than others - or the one you walk into - which is harder. I find I get along much better with training partners when a significant proportion of our sparring is light because we both have a chance to see when the power is intentional, when it's not and even when being hit hard is our own fault. It's less personal.

Maybe you know all this but I just thought I'd reiterate it since being the gym midget power control has been essential for me. Plus i thought you probably wouldn't have put this post up if you didn't want others opinions.