The best is for you to try both techniques, that's what i did. And it's very fun to experiment.
This one is made of 40 photos of 25 seconds exposure, stacked in software.
This one is a 25 minutes exposure using bulb mode, with the kr, at f/5.6 and ISO200.
Here's a 12 minutes exposure
And finally, this is not a trail shot, just wanted to see the Kr ISO quality shooting wide open with my 77mm limited. This is a 6 seconds exposure at f/1.8 and ISO 800. For those wondering, this is a part of the Orion constellation, the 3 vertical stars being the belt and the red cloud in the middle is M42, the nebulae.
I am very happy with the details and the nice colors.
The Kr is an excellent performer in my opinion.
As I said, just try and you'll get some good stuff, you just need to find an interesting spot to shoot from, the darker the better.