Thats a nice paint scheme you have there Stuw - bright and colourful - perfect for an off-shore powerboat!
My Swordsman build is taking a lot of my bench time at the moment, but I did take a look at setting my small bandsaw up again with the little jig that I made to cut some more strakes to add to my Javelin and Rapier hulls as neither of them have any strakes fitted.
I restored my Rapier and bought the Javelin on eBay, so I never built either of them from new, but neither builder of the originals fitted any strakes.
The slightly over-size strakes that I intend making will look nice and aggressive (same as I have just fitted to my Swordsman build) - so even if they make no difference to the performance - they will look good! I think 3 on each side will look "right" but I will check it when I have them cut as being a littler bigger, two on each side may be enough and look better.
My Rapier is nice and quick when running only on 2 cell 5600mah 65C LiPo cells on our club lake, but on more open water I can change to 3S or 4S (using a smaller dia prop) and it could easily get a bit "silly"
I had a similar problem as you have with the prop shaft on my Rapier - it was an old 2BA size and I fitted an M5 stainless inner shaft - and that did need the old shaft bearing opening-out slightly. If you prefer to change the shaft and fit a new one - this is how I change mine:-
After taking everything out of your hull (including the inner shaft) scrape away any adhesive/filler around the shaft that you can get to, and then give the end of the shaft a sharp bang with a heavy hammer. This usually shatters any old glass fibre/epoxy/filler/cyno that may have been used when the shaft was fitted.
Once loose, you can wiggle it about and remove any fractured lumps of old hardened glue/filler etc until you can withdraw the old prop shaft. Once the old shaft is out of the hull, you can clean everything up and fit the new M5 shaft.
As a matter of interest I may still have the old 2BA inner shaft that I removed from my Rapier. I rolled it on glass to check it, and it still runs straight and true. When I take a good look at my Javelin I will see if the inner shaft runs true on glass and if does and there isn't any play in the bearings - it can stay in the boat. If anything is wrong I will remove it (using the method described) and order a new one from ModelBoatBits to replace it.
You will see that the new M5 shafts have a slightly smaller dia brass outer tube than the old heavy brass tubes used in the earlier 2BA propshafts, so you will gain a little more "wriggle room" to get your new shaft to run straight and centrally in your hull when you fit your new shaft.
Stay safe!
Bob.