I've run into several problems trying to get conditional variants to work the way I would expect them to. First, if you use certain characters in group names and/or variant names, the conditional functionality breaks, but doesn't throw an error, it just doesn't display the conditional group. I experienced this when using a slash in the names (ex. Guest/Spouse).
The more troubling problem has to do with displaying conditional variants as checkboxes that include a price change. For example, I have a regular variant with a Yes/No radio button list for "Will Guest-Spouse Attend". If yes, display the variants in the group "Guest-Spouse Activities", which include a list of checkboxes for the items they can sign up for. Examples in the conditional variant group include "Golf" with a $50 uplift, "Wed Night Dinner" with a $30 uplift and "Thurs Night Mixer" with a $25 uplift. These display properly, but it seems that only the first item checked actuall increases the price by the proper amount. If you check all, then uncheck something, the price changes based on the first thing it picks up that is still checked.
So, basically the checkboxes, as with the textboxes, aren't really usable as conditional variants, except in the most basic fashion. The various issues I've found with conditional variants can certainly be overcome by not using them and making the user experience less than precise, but it's a little disappointing to see so many issues with a released version of the product.
Also, the controller/hard drive example of conditional variants in your manual on pages 104-105 isn't setup properly. You reference the wrong groups (RAID as the conditional in the regular variant, then you give the conditional example as SCSI). I haven't gotten around to validating how conditional variants perform if they contain required variants, but will post what I find.