I am in need of opinions on the Elinchrom Digital Style RX and the Style BX monolights. Has anyone used either of these? Pros and Cons of each? Quality and temp. of light produced?

Does anyone use monolights as hairlights? I have been told they are too heavy to use with a softbox, however this particular light only weighs 5.75lbs. I will be photographing a lot of children so safety is a big issue.

I am new to studio photography and my plan is to use Elinchrom 600RX (guide number on this is F-90 @ 3.3M @ ISO 100, 1/250 with a 48° Reflector) for my main light (do I need more power for a large softbox?---the 1200RX has a guide number of F-128.1 @ 3.3' @ISO 100, 1/250, with 48° Reflector but also has a steep price!).

I am afraid that the 400BX will not have enough power (guide number on this is F/64.5 @ 1M, @ 100 ISO, 1/250 sec, with 48° reflector ).

I was going to eventually get a 600RX for fill (when needed) and 300RX (guide number F-45 @ 3.3' @ISO 100, 1/250, with 48° Reflector) or 600RX for a hairlight.

I will also be doing high-key--what will I need to light my background? I was thinking of possibly starting with the BX units and later use them for background lights, or hair lights.
I want to buy the minimum for now and build up, so versatility and practicality are big issues for me.

I am just getting started here, so no information is too basic. Any opinions or advice is greatly appreciated.