Can sailors that have used both whisker pole and spinnaker pole please give some pros & cons for each.
On my Pearson 30 I used a telescoping whisker pole extended by line. I had a 155% furling/reefing genoa on the boat most of the time. So, I could shorten the sail and shorten the pole as well if I wished to go wing-'n-wing under reduced sail, which I often did. It was a bit of work at times to muscle out the telescope and cleat the line. On a big boat like yours that might be tough work. The inboard fitting of the pole fastened to a mast padeye, one on either side, and was not adjustable up or down the mast.
The 38-ft boat I have now has only a spinnaker pole and previously a 135% furling/reefing genoa. Clearly, the design intent is that if I wish to go DDW then I should hoist the symmetrical spinnaker and use the pole as intended. That's a bit of a problem sailing with only the wife and me b/c it's too much work most of the time on a leisurely sail to deploy and recover the chute, especially if the wind is up and you have to remained focused on trimming while it is up, etc. I know; people do it all of the time and it's no big deal to them. But to go wing--'n-wing on the Bavaria I had to shorten the furling No. 1 so the spinnaker pole could usefully extend the sail, etc. I'd do this if going far; but for short gybes just to get position I'd goose-wing the genny (i.e., fly it opposite the main on the weather side w/o the pole up), which is very effective for short course corrections. (It works only if you can sail far enough off the wind to keep the genoa full w/o getting by the lee on the mainsail and crash gybing the boom.
)
I now have a No.2 furling/reefing genoa on the Bavaria so the spinnaker pole is a much better fit for sailing DDW wing-'n-wing. But, I can still adjust the fit by furling the sail in further and/or by raising the inboard (mast-slide) end of pole to
effectively shorten its extension. (The inboard end is not fixed to a padeye on the mast.) For folks who buy a fixed length whisker pole, that is what they do--raise/lower the inboard end of the pole on a mast slide to adjust its extension some out/in from the boat, etc. This is easier and faster than running in/out the whisker pole telescope using a line.
So, your money--your boat as Stu likes to remind. You can always have made a custom fixed-length whisker pole to fit your present headsail configuration that will work perfectly, but you may have to install a mast-slide system if adjustments might be needed. If you get a different-sized sail later; get another pole. The fixed-length whisker pole is tapered at the outboard end, I believe
; which lightens it some. That's another way in which it differs from a spinnaker pole, which is not tapered in addition to being restricted in length to the J-dimension of your boat, etc. In terms of wielding--and you have bucks--consider a carbon fiber pole.