Dennis,
I bought a used Sensenich prop just like the one you plan to order. I haven't had a chance to test it yet, but believe it will provide a higher cruise speed while providing a very similar climb rate to the longer Warp 3 blade. I base that on a few friends that fly the Sensenich 3 blade on their Vans RV12 LSA's. (they say "it is the prop to have on the RV12").
Granted, our Highlanders are at the other end of the LSA spectrum compared to the RV12. And we have a lot more available ground clearance than an RV12, so we have the option of running the longer props that generally perform better in the STOL environment. But if a guy is looking for a better overall cruise speed while still being able to do respectable STOL work, I think the 3 blade Sensenich will be a great choice. (BTW - when assembled it actually has a 69 inch diameter - I measured mine)
I've always liked the look of the Sensenich scimitar shaped blade, thinking it should be a very efficient prop. And it certainly is a beautiful prop. So when I ran into a good deal on one I jumped on it. And if nothing else, I thought it would at least be fun to experiment with. I originally thought I might replace the IVO on my 80 hp Kitfox amphib with it. But my 68 inch IVO 3 blade (IFA) on that performs so amazingly well that I hate to change it out (even though I'm not real fond of the flimsy blade and the problematic leading edge tape). So I think I might just run this one on my next Highlander. If it works as well as my 2 blade 70 inch Sensenich does on my current Highlander, I'll be more than happy with it. I know there are much better props out there for maximizing the STOL capabilities of our airplanes. But since our planes do so much better for STOL than anything else out there, I'm willing to sacrifice a little bit of that STOL in favor of some extra cruise speed that gets me to places faster, and more efficiently. I think so many times we have a tendency to get wrapped up in getting more and more STOL ability from our airplanes, and tend to forget that if we can stay more reasonably propped that our Highlanders are actually pretty good airplanes for going places as well as booney bashing.
I know long props is the current trend as it optimizes STOL performance. But flying floats actually demands more prop and engine performance than does STOL (adding a set of amphibs is like flying around with 3 people in your airplane all the time...). So I am well aware of the needs for getting the most out of your prop. But what I've learned in the last 400+ hours of flying my 80 hp Kitfox amphib is that we have the technology today in props to achieve better cruise speed while still getting reasonable STOL performance.
A good example of that is when I tested 3 different IVO prop blade lengths (all the same airfoil) to learn that an old cut down 66 inch 3 blade IVO gave me 8 mph more top speed than a 72 inch, but almost 200 fpm less climb rate. So I ultimately settled in on a 68 inch 3 blade IVO. It provided a very similar top end to the 66 inch prop, but was only 50 fpm less climb than the 72 inch. So my experimentation paid off. And even though I've shared my results with many of my Kitfox buddies, they refuse to leave their 72 inch warp props. Yet they comment about how "fast" my Kitfox is compared to everyone elses, and believe it is in the rigging, streamlining, etc.?
The only real downside I found of the 68 vs the 72 is when you are landing the 72 inch provides much more braking effect. But hey, that's what slips are for, right? And while I think the Sensenich 3 blade is a very nice propeller, I think they need to get rid of their "adjusting pin" concept, as people that have used the prop complained that the concept sounds a lot better than it works (the two blade I have also had some new novel "adjustment knob" that didn't work either). Save money on pins and buy a Harbor Freight $30 digital angle gauge and set all 3 blades with that. I can't begin to tell you how many guys have complained about poor prop performance only to learn that their blades are not set the same (the equivalent of having one wing on your plane set to a different angle of incidence than the other

)
With all that said, I can appreciate what you are trying to accomplish Dennis. I think it will be interesting to see how a streamlined Highlander like yours will do with what I believe to be an ultra efficient propeller.
Paul