I have a cheap (in price) chinese copy of the SLR zoom, and it CAN be flimsy or unbalanced, but that's pretty much only down to how you set it up, there's a lot more control over the positioning than a regular tripod, and positions where the weight isn't distributed well are easily obtainable, whereas they'd be impossible on a normal tripod (this is both a blessing and a curse).
The solution is to make sure that you spend a while experimenting with it, and carefully feeling out where the centre of balance is, and how it interacts with positioning the legs. Practice until you have a good feel for it, and it'll work fine for you when you need it to.