I just got my first set of monolight strobes through Calumet, with umbrellas. But I've been using strobes at work for about a year now, and I've worked with professional commercial shooters for 25 years. The only thing I'd say is...never say never when it comes to softboxes.
For product shooting, you have to think beyond just throwing up the lights and popping away. The boxes do diffuse the best, but you'll do different things depending on the subject.
I've been "lurking" on G1 long enough to recognize that the really good people shooters here that you can learn from, all seem to use softboxes like the commercial shooters.
Sure they take up more room to store than umbrellas, but it's not like they take up a lot of room. Think flexibility for your overall kit.