I've done a few trays, odd shaped bowls involving deep cuts etc. It's just easier and a lot quicker with the router upgrade. Doing delicate carving of reliefs, finer fretwork type cutouts, lettering etc the stock spindle copes well.
I just prefer the much faster speed rates achievable with the dewalt. You can really take advantage of the speed and feed rate the genmitsu can offer, with stock spindle you need more patience, it will still do the job, but bigger stuff it can take 6 times longer, even more if its really hard wood