Personally using the KISS rule and the almighty dollar rule, I would not go this route. If you struck something hard it would be expensive to repair if damaged and I would also be afraid of a swinging shaft if a u-joint let go however unlikely. It has its place in certain instances, but I think a well installed engine with coupling faced for zero zero run out, shaft checked, Barry controls mount, lap fitted prop, and maintained cutlass bearing will be as good. There are many reasons for vibrations not all related just to the running gear though all components need to be checked especially if new since shafts and couplings are almost never to spec. Look into aerating the prop wash also if you are looking for a super quiet cruise The oil bath syst and u joints just seems too complicated and would need to be serviced at some point seal wise as everything wears out at some point under use with many things wearing from no use. Looking forward to your build on this site what engine HP are you going with and I assume Cummins of course.
The airation thing definatly works but the evelution system won't help that anyway. What it does is basically seperates the engine from the drive train so you can have the softests mounts on the engine that money can buy. The engine kind of floats in the engine bed and all the force is put on where the shaft is bulkheaded to the hull. If you look at the rear bulkhead where the shaft comes in all the pressure is there. The airation block puts a layer of air between the hull and the water so the water coming off the top of the wheel does not slap the bottom of the hull.
With that said, I had an evelution shaft in my last 36NB. I would never put one in again. Not because I ever had a problem but because there are so many problems that can happen with it. There are a ton of moving parts on that thing and a ton of possible failure. You have to change the shaft oil every season, lube universals, and god forbid the thing goes under water. Imagine how fast the boat would sink if that rear universal let go at 2000rpms.
Yes, that boat had a big engine, 122p volvo 3500lbs with gear. You could put a cup of coffee on the dash at 23 knots and there would hardly be a ripple in it. It was a pain in the ass to set up though, you have to have the proper amount of roll to the universals or they say they will fail. I miss the speed of that boat!
Aquadrive is the KISS solution. No oil incased bath. Just a short shaft that goes to a thrust bearing and then CV joints on the other side of the thrust bearing and engine with a tubular shaft in between. NO U-joints..these can pulse...CV's do not and allow dissimilar angles on either side of the tubular shaft.
I have the Evoution drive in my rig. I won't argue there is potential for failure but i don't believe anymore so than other setups. My system includes a loop to catch the drive shaft in case of failure. The ride is very smooth and anyone who has fished with me claims it is one of the quietest DE around. I bought my boat used so I did not have to make the choice, but after running it for a while I would say I like it.