Will this Sony CX280 be good enough for video ?

Hi Marbury,
it all depends on your budget... I would buy this http://www.bhphotovideo.com/c/product/397662-USA/Canon_0344B002AA_24_105mm_f_4L_IS_USM.html:

I have a 550D with this http://www.bhphotovideo.com/c/product/596257-REG/Sigma_571101_24_70mm_f_2_8_IF_EX.html and I have to say I'm not very satisfied...

Optical stabilization is a must, IMHO...

Thanks for that. I may go for the Canon then :-)

For footage on a dslr optical stabilization is not needed and if you are using a tripod it should always be turned off. When turned on while using a tripod and shooting footage it will try to stabilize the footage which has no movement so it will actually input motion or much higher level of jello. It helps on handheld photos but that about all it's good for.

I also have a 24-70 f2.8 Sigma that is a very good lens and much less expensive than the Canon L lens. I still believe the Canon L lens family is a higher quality overall but more expensive.

Well you have to pay to get better quality. I can't wait to get going with video. Not too bothered about the magic lantern (looks very complicated) I can edit my footage on the PC with software rather than in camera.

Magic lantern doesn't really do in camera processing. It adds additional menu items and better capabilities to the existing Canon firmware. IMHO straight from camera uploading without cropping and "minor" adjustment is not the best process. You still need a good computer and good software.

I am not quite sure weather to go for a full frame Canon or Nikon that shoots video. The reason being for my creative landscapes etc. Kill 2 birds with one stone and get a decent stills camera. The 600D (not sure why people call it a T3i) looks a great camera for the money BUT you lose so much of the wide angle because of the smaller sensor. Decisions decisions !