I have the 5.5 degree rake on my RoadSmith, and I'm very glad I do. Yes, the greater the degree of rake, the more sensitive the front end is to any input to the bars, but to avoid that, you must give up steering ease. It's been my observation that anyone who transitions to a trike must get used to the difference in handling. The trike steers whereas the two wheelers respond to countersteering. The two wheeler requires much less effort and pressure to turn. My first trike experience was with a CSC kit on a GL1500, which had the 6 degree rake kit on it. For about a month, I thought I'd really made a mistake. Everytime I moved my body or even thought about moving, it seemed, the trike ducked or darted around a bit. I couldn't hold a straight line going down the road at first.
Then I realized the trike wants to go straight, and I realized that I was gripping the bars much to strongly and attempting to force the trike to go straight. I was "over driving" the thing! I relaxed my hands, my arms, and my chest muscles, keeping my hands on the grips with my fingers and thumbs curved around the grips without actually gripping them. Instant relief!! Then, with a bit of experimentation and experience, I learned how to make steering inputs to the bar without overdoing it.
Later experiences riding trikes with no or lesser degree rake showed me the real difference between the effort to steer my trike and those. I know ride my trike pretty much like I did my two wheeler, hands and arms relaxed but on the grips most all the time. I occasionally remove a hand for some purpose or other, and I continue on my course down the roadway with no concern. I don't even think about how the machine handles because I'm used to it.
My point is that you have to get used to whichever trike you buy to ride, even if you've ridden a trike before. My RoadSmith handles with less sensitivity to bar inputs because it has an 8 inch longer wheelbase, whichc also makes it much more comfortable to ride coupled with the IRS rear end. I absolutely love it!!! I can tell you that I am more comfortable with the handling of this machine than I ever was with a two wheeler!! Yes, I'll hold you against the wall and extoll the virtues of the RoadSmith kit as long as you'll hold still. Please keep in mind that my opinion exists with lots of experience with both two wheelers and trikes ... less on all brands of trikes, especially over full days of riding, but enough miles to tell how well they handle and how comfortable they are for me and for my wife as well.
The larger the degree of rake, the more sensitive the machine will be to your inputs, but do not think it is difficult to get used to that, especially with the longer wheelbased kits. I'd say you'll be used to any of them in about the same time frame of riding. And that won't happen in a short test ride or two ... it takes some time in the saddle, preferably a few hours at a time. Doing that will speed up the transition time considerably!