I've brought a batch of the alpkit jackels for a training group, and I've found they are a slightly lower quality than a jetboil. Now that Jetboil's patent has expired there are various copies, alpkit appears (to me) to be a very well priced branded version of the fire maple (the jackel has an alpkit branded neoprene sleeve). A few of the jackels needed the Piezo igniter bending nearer to the gas outlet to work consistently. Also, the pot stand that comes with it stopped the igniter working, as it was sparking against that, too far from the gas. Weight wise there was very little difference. i found a gas bottle didn't fit into the body of the jackel, as the gas burner section is the wrong shape. Not a massive problem, but it was a convenient feature of the jetboil (i've the zip and the flash btw) to have it all fit together.
Fire maple have done an updated version I've seen on aliexpress.com called (firestar) FMS-X2. It looks like it's moved nearer to being a jetboil. I'm not planning to buy one.
One thing to note if you have an old jetboil, keep the orange stand, as it'll be needed with the jackel if your using it with the pot adapter and a frying pan.
There is also the primus lite and the msr windburner, both are jetboil price or more. My verdict is the jackel is 'good enough', but take a firestriker to light it just in case.