I use Winclone to resize and deploy Bootcamp installs on a regular basis. I manage about 75 dual boot Macs as a significant part of my job.
It works exactly as described.
Once Winclone has made an image of the shrunken Windows filesystem, partition management is done via Disk Utility in OS X. The boot process works the same whether the partition is created via the Boot Camp Assistant or with Disk Utility, then restored from the Winclone image. Winclone does all of what's needed to make Windows boot properly.
Macworld has a review of Winclone 4 (it's now up to version 5) here:
http://www.macworld.com/article/204...-a-must-have-utility-for-boot-camp-users.html