I think if you decant the liquid off the starter, much of the less floculant (and higher attentuation) yeast will be separated from the rest. This changes the characteristics of your yeast population, especially over several generations. I'd say take a cell count of the liquid you wish to remove, if you have a reasonable amount then you altered the population characteristics. Especially if there is enough yeast in suspension to start another batch, then you have created two very different results. One beer will come out dryer and less clear than the other. I guess some worry about the additional fermentation byproducts that you can smell in the starter, but it should not make a big difference, yeast reabsorb a fraction of what they emit, more so the less flocculent they are (in general). So by losing the less floculent fraction of the population you lose a part of the yeast's ability to reabsorb the by products - but then you added more so I guess it depends on yeast? I'd say throw it all in.