I've added a row of pieced blocks to a few of the quilts I've made recently and didn't notice a problem with any bulkiness when quilting. I imagine a lot has to do with what machine you're quilting on, the needle type/size you're using and the thread type/size?
Best part is that it filled the gap I needed to widen the queen sized backing and it's so stinkin' cute to have a little something on the backside
Go for it!
Christine