Bryan,
You've asked a number of very nuanced questions that I'll do my best to answer, but first, it's important to note that the double claw in the EE is
not an authentic example. It's a post war re-creation and my hope is that publicly ousting it saves a potential buyer from making a HUGE mistake.
With that out of the way, there are many answers to the questions you've posed. This response will become a novel if I delve into each subject, so I'm going to have to keep this fairly general. With that in mind, the main reasons for multiple variations are as follows:
1) The variations evolved slowly overtime. When deficiencies were noted, improvements were made which then spurred the creation of additional variations (e.g. low turret to high turret AND short side rail to long side rail).
2) The Nazis developed a decentralized procurement system which set the stage for companies to compete against each other instead of working towards a common goal. This resulted in many variations and as the war progressed, it became difficult for the factories to re-tool so the German High Command allowed the variations to exist as long as the factories could meet their delivery schedules.
3) Each branch of the Wehrmacht + SS was constantly competing for resources. This meant that it was not uncommon for certain branches to independently broker side deals with various factories, which then spurred unique variations (the SS was notorious for doing this).
With respect to windage, these adjustments could typically be made from the rear mount (e.g. low / high turrets).
Regarding accuracy, the rifles were carefully selected at the factory once they had been test fired and performed favourably (i.e. they were not selected at random).
I hope this information was helpful to you. Now, I wish I could say that I owned an original double claw, but sadly I do not. I do however own an original low turret, high turret and zf41. Each example is produced by Oberdorf. Attached are a few pics for you guys to peruse.
Cheers,
SoH
Group:
High Turret: