In my humble opinion, all variations that connect the Finch and Sheppard routes are tricky, and might create more problems than they solve.
Sending the Finch LRT across Yonge to Don Mills, and going down to Sheppard? That kind of bastardizes the transit service on Finch east of Don Mills; the route serving that section would have to either terminate at Don Mills and force a linear transfer for those who travel towards Yonge, or run to Yonge overlapping with the Finch - Don Mills LRT.
Shifting the Finch LRT to Sheppard West before it hits Yonge, for example using the Finch - Dufferin - Sheppard route? That's better in not affecting Finch East, but inconveniences the riders travelling from Finch West and heading to Yonge & Finch, or Yonge north of Finch. Those riders would have to either accept a detour, south on Dufferin then back north on Yonge, or take a linear transfer to a bus in order to keep going along Finch.
A relatively passable option, that I've seen in this thread many pages ago, is to keep the LRT on Finch until it reachess Beecroft, and then go down Beecroft to Sheppard. Then the Finch - Sheppard connection will be created, and at the same time, the riders will be able to transfer to subway at Finch although the tunnel will be longish (200 m).
But the simplest and most straightforward solution is to keep the Finch and Sheppard routes separate. Finch LRT could be extended east, first to Yonge and then deep into Scarborough, only turning south once it reaches McCowan and connecting to the SSE terminus. And later, the Sheppard line can be extended both ways, possibly after converting it to light metro / OL type technology.
