Your point about joining the company and owning shares in a pool of machines is good idea, but I'm assuming that early adopter's would have to share their proceeds with eveyrone who bought in later, no? That could be problematic.
No. Early adopters should get their reward for being early adopters (I'm a late adopter).
Lets say that 4 Saturns have been delivered and each one generates 1BTC every week. Every Sunday, at midnight, all the generated bitcoins are distributed to the shareholders.
Everybody with a share in the first 4 Saturn has 11 shares in the Company. This means that there are a total of 3432 (4x78x11) shares in the company.
On Sunday, at midnight, every Company share gets 4/3432 BTC = 0.0011655 BTC.
On Wednesday, Saturn #5 is delivered and powered on. Over the following 3.5 days (until midnight Sunday) it generates 0.5 BTC.
On Sunday, at midnight, every shareholder of Saturn #5 gets 0.0064103 BTC (0.5/78). Every share in the Company gets 4/3432 BTC. 858 (11x78) new shares are created in the Company and exchanged with the owners of Saturn #5.
The company now has 5 Saturns and there are now 4290 shares in the company.
The following Sunday 5 bitcoins have been generated over the previous 7 days and each share in the Company get 5/4290 BTC = 0.0011655 BTC.