Could this be an alternative to the Clarisonic?

I've been reading so many reviews on the Clarisonic lately, which many of you are already familiar with. This nifty little tool is supposed to aid in giving a deeper more effective cleansing and exfoliates your skin to boot. The thoughts of more radiant and healthier skin certainly appeal. Sounds great, well right up to the point where you get to the price. At over £150 for the cheaper version, I believe, it's just way out of my price range right now. However, I have just spotted that Sigma have released their own version, which they have simply labelled the 'cleansing and polishing tool'. At $39 plus postage, this seems much more feasible for my ailing wallet, plus it comes with 3 heads for different skin types. That was an issue that many reviewers seemed to have with the Clarisonic, they found the brush head they used was either too hard or too soft. What I'd like to know is if anyone out there has tried both companies' versions. Now, that would be an interesting comparison, I'd be eager to know their findings.

The only problem I have with the idea of using what looks like a large electric tootbrush on my face is... could this be counterproductive? Is it a good idea to over buff the skin? Could this do more damage than good? I don't know, is the simple answer. With sensitive skin that's prone to redness,  I have to be careful with exfoliation and could easily over do it. I tend to think the muslin cloth method at a meager couple of euros a pop might actually be a much wiser investment for me, at least for now.

What are your thoughts on this?