Steph,
try this sometime. Inject the breast with a 18g spinal needle and 60 cc syringe with 500-700cc from a mix of 1L NS + 1 amp 1:100,000 epi. Let that stand for about 10-15 mins. Take 3 or 4 mm liposuction cannulas and tunnel (not hooked up to suction) the hell of the skin flaps using your off hand for guidance. Make your mastectomy incision for your nipple sparing approach and you will see that you have essentially degloved the parenchyma at the sub-cutaneous/parenchyma plane with just a handful of retained dermal ligaments to divide with scissors. The breast will then literally peel of the fascia with light cautery on the pectoralis side and you can deliver it out en bloc having had to use very minimal cautery. This is a really slick way to do this and minimize collateral damage to the flaps prior to immeadiate reconstruction.
Try this on a small prophylactic mastectomy sometime as that's the easiest way to learn this.