RE: Feedback on partnering or replacing an ???05 Evo 74 for decent waves?
Interesting thoughts, Stev-O, and obviously you have both experience and have thought about these questions yourself for a while.
I want to start of by saying that EVOs surely can be ridden very front foot, sail forwards style in a variety of waves incuding mast+ stuff. Just look at Scotty (on the video on the Severne site fx). Also mortals like myself can do this with the right technique. You will always loose a bit of the direct feel in a fast bottom turn compared to a "trad" design, but you can still go fast and be precise. I would say that the EVO 70 is noticeably better in these conditions than the 74 though. It has lots of more "drive" and are more natural at speed. Also the 2006 EVO 83 and 07 80 are more drivey in the character.
Conversely, looking at Pure Acids, they are also more all round than one might think and with the right technique you can rip on them also in cross on mushy stuff. Pretty much any Acid or Pure Acid will give you a more direct feel in a fast bottom turn but in slow waves you will either need to feed the board with sail power or have a very exact technique to make it go.
With every aspect of technique and tuning reasonably wired (ideal sail and fin setup can differ a bit between the two) what differs between EVO and Pure Acid is how you want to approach the wave. Both _can_ do anything, but the EVO prefers vertical riding and turning in the pocker while the Pure Acids rather likes drawn out turns and faster cutbacks. As an illustration (in small wave, but still), on http://www.olah.se/Windsurfing/Guincho-06/index.html pic 2-6 show a EVO-typical approach while pic 7-12 shows the Acid-typical approach. IN htis case both turns are executed on and EVO which kind of illustrated my point about both boards being able to do anything, but it takes a more "exact approach" to get away with the second turn on the EVO.
So, to get to your questions and three alternatives, I would say the following.
1. (Partner EVO 74 with Acid). You're looking at three versions of the 74 that are very different. The 04 is the classic board based on Scottys old Acid 70. A great shape while I loved at the time. The 05 is a completely new shape, v bottom instead on concave. The 06 is based on an EVO 70 but drawn out, but still has a classic feel to it more than an EVO feel. Out of these, I personally prefer the 05. It has a very nice flow through the turns to it and just feels very nice on a wave. I think the 04 handles more wind and rougher waters better though, and the 06 is probably the faster onto a plane and the one that handles slow waves with little sail power the best. The 04 handles onshore frontside turning well too, but needs a lot of sail drive. The 05 is more flow-precision-finesse" than just pure power (these differences are more due to bottom shape than width, I would say).
2 (sell E74 get PA74). If you go this route I would definitely recommend the 07 PA74. There are conditions when the PA74 will simply not work as well as the EVO regardless of how good you work it, but since you have bigger boards too, I think you will find it just as all round as the EVO (or more) is you just like its style of turning. The 07 PA 74 is acombination os a tricky v layout, fast rocker, semi-soft rails and a semi round outline and you kind of use the round outline to not stall at slower speeds and the fast rocker and spiraling v to lock in a fast bottom turn and have a really solid carving tail at speed. A REALLY great board. Since you allready have spent time on the EVO, you knwo what is possible to do in bad conditions and with this mindset and some sail power and technique you can (again...) make the PA74 do great things in these conditions too.
3. (Keep EVO - adjust technique). If you feel that you after all want to stay EVO-style, at your (still pretty light) weight I think the EVO 70 should be the clear ticket to bigger and faster waves. You will loose only very little in slower stuff (some looseness and some "volume comfort"). Even for me (68kg) the E70 is a great board in fast (also choppy) waves when you handle it right and with some more weight it has potational of being even better. The 07 70 is a still better board for faster, bigger waves. If you go for a EVO 70, I would in the long run look into changing the Acid 88 for an EVO 83 (or maybe 07 E80). Then you can benefit from dialing in your technique for the EVO also when conditions dictates a bigger board.
So, no clear answers, but maybe some (more) food for thought.
BTW, I have friends that have changed from EVOs to Acids. Some of them got happy and some changed back. Doing such a change back and forth can be a good thing. It makes you realize that any board is a compromise and that finding the right one is learning to live with compromising some aspects of the ride that you one one hand may like but on the other hand don't find as vital to your wave sailing expirence as some other aspect.