I'm not familiar with the BD "Contact", but I assume they have Scottish bindings. If so, one concern I would have is interfering with the circulation in your feet, since the bindings will need to be reasonably snug and your feet may swell at that altitude. You will be on the route for probably a minimum of 8 hours RT and cold feet would be no joke. Mesh uppers don't leave much of a margin for error. I'd consider a sturdier boot if I were you. The MR on Whitney, even in April, is considered a winter climb with all that implies. Better safe than sorry.
Also, if you are ascending a fixed rope, presumably using an ascender of some sort, you will be able to face in and scramble up a few quick steps in front point mode if necessary. Set your ascender up as high as you can, plant your ice ax high or use a hand hold if available, and up you go. You may also be able to stem. There will no doubt be other options that I haven't mentioned. Take what the terrain gives you. Also remember that you probably won't be the first party of the season. A lot of steps are likely to have been well kicked in by the time you go up, barring a lot of fresh snow, offering not only foot placements, but potential hand holds as well. Have a great trip, Jim. One of my best friends is going to be down there in April, too. I'll tell her to be on the lookout for Jim Q. ;)