Just looked at your blog - and this is my very first impression . While many of the photos are really very good, what I find slightly disturbing in many of them is that the shadows are noisy while the highlights aren't. Must be related to the underexposing, as you explained above.
Which converter are you using? I use aperture and find it excellent for highlight recovery. It can save a stop with the GRDII (not GRDI). Of course, you may want the effect, in which case this comment is irrelevant.
Having said this, one still needs to make a choice whether to expose more for shadows or highlights with the small sensor cameras. GRDII is quite good, but I usually keep it on manual, because getting the exposure as desired is very important. Still you generally have to sacrifice something.