I haven't used Micro Mark's solution, so I can't say how well they work compared to other brands. I've personally use the MicroScale solutions. They have 2, 1 mild (micro-set) and 1 stronger (Micro-sol). In a few rare instances, very thin decals will find the micro-sol too aggressive, for those I'll just use micro-set.
I have also bought DACO brand recently and have heard this works well but is much stronger than the microscale stuff. I'm trying it out to see if it can save a me from applying 2 or 3 applications on stubborn decals.
However, some decals are just thicker than 'normal', the older Tamiya decals are often noted for this. Which is another reason many buy aftermarket ones instead.
You didn't say specifically, but the clear coat you add before decals is a gloss coat? The gloss coat gives a smoother surface for the decal to settle on.