Rotatrim cutters are excellent - especially their self-sharpening "knives".
There's one very necessary adjustement you need to make with those, however. The top plastic guide, for whatever reason, doe not line up with the edge of the base where the actual cut is made. It sits back several millimeters. The effect of this "flaw" is that when your print is in there ready to cut, you don't have a good feel as to exactly where the cut will be as you have no reference since the plastic guide is not directly over the cut to be.
So, you have to rig the guide and make line up with the edge so that when you look at the guide and the print below, that is exactly where your cut will be. This is especially important for very fine trimming. On mine, I had a spare pice of semi-rigid plastic so I replaced the entire piece with it.
I cannot comment on the virtues of the Kleencut however.
I, too, use a Rotatrim, but a smaller one, and have been pleased with it. Rotatrim is sort of the "gold standard" for cutters, but I've also heard (read, actually) good remarks about the Kleencut, which I think is less expensive.
For an inexpensive "post-production" tool, I have found the hand-held OLFA RTY-3/DX rotary cutter to be terrific. A hand-held rotary cutter much like those used to cut pizza, this one is equipped with a plastic pistol grip and is popular with quilters and leather-workers.
I use it to trim prints prior to mounting, over-hanging edges of mat windows, shipping labels, foam core, hinge tape, you name it.
This model has a 60mm cutting wheel, which I believe is better suited to the variety of tasks I use it for, as opposed to the models with 45mm blades where clearance becomes an issue, say with a sheet of foamcore. The well-conceived design features a squeeze handle and blade lock to expose and retract the circular razor blade. Replacement blades are pricey ($7) but you can buy a sharpener ($10) that will extend the life of
I use it in conjunction with a Logan straight-edge directly on my work
surface, a desk-high counter covered with 4x8 sheet of SINTRA (a high-density foam used for sign manufacturing) cutting surface. After a cut, there is hardly and evidence, unlike my X-Acto knife which leaves deep cuts in the same surface.
I've looked into getting a self-healing work surface (many sewing suppliers make cutting surfaces), but have found the SINTRA to be satisfactory in every way, and much more economical at $30 per 4x8 sheet compared to $150.
It doesn't match up to a flat bed rotary cutter from the standpoint of multiple repeat cuts in the dark, but I find it much more versatile in all other ways. My flat bed rotary cutter spends most of its time leaning against the wall.