I'm excited for this new slicer. As far as feature requests go, there are quite a few of mine implicitly included in my slicer thoughts post from a while back: https://groups.google.com/forum/?fromgroups=#!searchin/ultimaker/lawrence$20johnston%7Csort:date/ultimaker/5C1uAUz6JvE/KufYdLe3OuAJ
Some excerpts from the linked post (things that I find KISSlicer does better than the current Cura):
* KISSlicer has a nice feature where it will print several layers of semi-sparse infill (much closer together than normal sparse infill) before top-skins, which tends to make the top-skin print much nicer with lower infill settings (e.g. ~20%). In Cura you have to increase the top/bottom thickness to get the top-skins looking as nice, which affects both top and bottom-skins and prints more completely solid layers.
* KISSlicer supports printing upskins covering only part of a layer better, as Cura (i.e. Skeinforge) will usually make significantly more of the layer solid than really needs to be so.
* KISSlicer supports varying speed based on the extrusion kind (perimeter, top/bottom-skin and support, sparse infill). This is great for reducing print time by speeding up sparse infill.
* I prefer KISSlicer's support in that it generates sparse support up until a couple layers before it's needed and then switches to denser support up to where the print will rest on it. Saves filament for basically no downside.
* KISSlicer produces the full number of perimeters for large (and/or supported) overhangs, whereas Cura seems to go into some sort of bridging mode and only produce a single perimeter no matter how many are configured.
* KISSlicer's stacked layer implementation is such that the stacked layers do not lie directly on top of one another if the object is not perfectly vertical (it prints the same perimiters it would if you'd configured layers of half the size, but only prints infill every other layer) whereas Cura's just generates layers that are the thickness you configured but prints the perimeter twice at half thickness (so the two perimeter layers always lie directly on top of one another, even when the object is not completely vertical). I prefer KISSlicer's implementation, as the outside looks much better any time the object isn't completely vertical. Cura's implementation might have a small advantage in that the infill is always touching both stacked perimeters, but in most cases I would prefer the outside looking better.
* KISSlicer has a crowning feature, where it each layer it will attempt to fill in small gaps where there's no room for infill but the perimeters don't quite meet up. In concept, this is awesome, and in implementation, it's often awesome, but occasionally it can be a PITA. Especially for an object which has a lot of these tiny gaps on each layer (a half-sized octopus, say), there can be easily a half dozen or more tiny jump-prime-extrude extremely small amount-retract-repeat sequences each layer which travel all over the model which take up a lot of time and tend to slightly over extrude plastic in those areas due to the time spent priming and retracting. I do need to mess around a bit more with the crowning threshold setting to see if I can improve this. [NOTE: It sounds like you've already come up with your own solution to this, but I'm listing it in hopes that you can avoid the issues with KISSlicer's implementation, though even comb + retract only on jumps will help significantly I think.]