If you shoot lots of video, you really would be better off with an actual video camera/recorder. There are limits to do what you can do with a DSLR. First and foremost among the limits is the issue of the image sensor overheating, and shutting down the camera until it sufficiently cools.
DSLRs mostly use CMOS sensors, which are best for high resolution in short bursts, like taking stills. CMOS sensors can overheat quickly with extended use, like when shooting video. Camcorders frequently use CCD sensors, which do NOT have as high of a resolution, but can withstand extended use without overheating, like when shooting video.
Back to your question:
I have not used that Sigma lens, so I cannot speak about it's image quality.
If one were shooting stills with that Sigma lens, I would not think image stabilization would be particularly missed under most circumstances. The lens is pretty fast, f/1.8, so you can use faster shutter speeds. I shoot stills with a Canon EF 16-35 f/2.8L IS II USM, which lacks Image Stabilization, and I really don't miss it.
Perhaps what you really need is a camera stabilizer, not a lens with image stabilization. A stabilizer would work with your entire arsenal of lenses, and would only help to augment whatever lenses you own that do include IS.
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