captou

As long as you use a fullframe (24x36mm format) master lens, then both the 0.71x ULTRA and 0.64x XL will work fine.  The ULTRA is a little better corrected in the outer part of the image, but this is mainly important if you want critically sharp results at f/1.0 with a Sigma ART or Zeiss Otus, and would not be noticeable with a slow lens like the Canon 24-105.  If you plan to use an APS-C lens such as the Canon 17-55/2.8, then you should be aware that you may encounter slight vignetting when shooting HD (not 4k) with the 0.64x XL.  The reason for this is that even though the XL itself covers the entire m43 image just fine, the image circle of the lens is too small to cover after it is multiplied by 0.64.

​I agree it's not worth the savings, but V batteries shouldn't blow up. It is possible, but unlikely since even Chinese brands have over-charge and power cut off failsafe circuitry. Keep in mind that many reputable brands from all fields in electronics manufacture in China. It's more about choosing the right Chinese knock-off -always a bit risky, though-.
Li-Po batteries are the dangerous ones. Even brand-name batteries can explode or go up in flames because they are volatile and have no safety circuitry. Its just a power cell (or several) with two cables, and all sorts of things could go wrong. That's what I don't like about drones and gimbals: no matter what brand you buy, if you store your gear in your studio you are at risk of having one of those batteries catching fire. I believe the only exception is the Letus Helix Jr, which has a conventional Li-Ion battery.

I just bought a camera (Nikon D5300) from the cheapest legitimate shop I could find - no problems, but it's also a UK based shops which means the camera has already gone through customs. And still, it was almost half price compared to the high street retailers. Like Cinegain said, if you do your research, you'll probably be fine. If you're not sure about a shop and can't find any reviews on it, perhaps it's best to leave it. Some shops from Hong Kong also offer to pay back any tax in case your item gets held at customs.
I've definitely had the "going cheap is expensive" experience but that was more to do with buying things like camera bags from no name brands - turns out, buying from the trusted brand, even if it's expensive, is just easier sometimes.

Apparently they'll also announce a new rebel camera (750D) next week - I wonder if the video specs on that are gonna be harbinger for the specs on the new 5d... it will obviously be lower spec'd but if it's just same old features that might mean the same old features on the 5d (for video). Who knows...