One of the significant differences between the RTAK and Basic #9 is the thickness. The Basic is thicker so it will be stronger and probably a better chopper if light effort is used, it will also bind less in soft woods and such. Because the RTAK is thinner it should have better penetration when moderate to high levels of force are used. However the difference in thickness is not really that great, and the performance could actually be effected much more significantly by the respective balance points, bevel geometry, and even the grip ergonomics. Little differences in design in these areas can make large ones in performance.
Besides the geometry the obvious difference in performance would come from the steel. Newt uses 1095 which is a decent blade steel and the Basic uses M-INFI which Busse Combat has made several impressive claims about and from what I have experienced so far they seem to be on the level. Now how much of a difference this makes will depend on how hard you are planning to push on the blade. Even at low stress levels you will notice a significant level of performance difference in regards to edge retention, ease of sharpening and durability in regards to the occasional mishap where the blade hits something you wish it didn't. The difference would really only start to standout heavily though if the blades were really stressed hard in those areas regarding strenght, toughness, and ductility, so if you are looking towards heavy impact work then this might be of interest. The steel differences also effect other areas such as corrosion resistance and ease of cleanup, both aspects which M-INFI performs very well in.
Both makers do have a realistic attitude about their knives and neither have a problem with you actually using them which is readily appearant if you talk to either or them. Both I am betting would be very good functional tools, and the Basic on paper, and from my experience with it, would seem to be able to handle high stress work better. I would appreciate any first hand experience in this regard though.
-Cliff