just scratching the surface
For quite some time, the Traxis 3500 didn't have its optical output working properly.
That was recently fixed.
It also is reported as a pretty fast blind-scan receiver.
Not sure of the other models in that brand.
If you look hard enough, there's probably some little niggling problem with each of the brands you've mentioned.
Often, the problem is quite trivial, and wouldn't affect the way most of us use 'em.
Another thing is price.
Would you pay twice as much to have some little problem fixed, and maybe put up with another?
The Viewsats seem to have an artificially inflated price due to them being favored by the hackers.
Supposedly, the Traxis' are not hacked, and the 3500 can be had for
half the price of most Viewsats.
The Coolsat 5000 has been a receiver favored by a number of the forum members for some time.
It cost midway between the other two, did most things quite well, but had a few minor secrets.
If you can get one of the less-desirable receivers cheap because it's used, is that a bargain?
Often it is!
In a lot of cases, many of the receiver companies have come out with new hardware recently, and it's hard to say how they all work without more extensive testing.
Some (many?) don't really make their own hardware; they buy it from various factories.
The latest Coolsat receivers have a different user interface, and we think that's because they come from a different manufacturer.
Point being,
you really have to ask about specific models, not just brands.