Thanks for the feed back!
I like the idea of knitting the sleeves in the round up 'til the sleeve cap starts, but I'm afraid that attaching it to the body might be difficult with two tubey shaped parts.
I haven't thought this one through properly but could I pick up stitches along the armhole (the shaped armhole) and keep them on two needles (one on every side). Knit the middle ten, or whatever number the pattern tells me to BO in the original design, and then transfer the next picked up stitch to be the first stitch on the row, knit and maybe increase stitches and then transfer the next picked up stitch to be the last on the row and so on... Sort of "knit in" the sleeve, row by row.
Did that make any sense?