Logic Masters Deutschland e.V.

I built this puzzle for the SudokuCon livestream fundraiser as a "competition style puzzle suitable for speed solving". Some similar things exist, but I believe this is a unique new constraint implementation. Have Fun!

Normal Sudoku Rules Apply.
Under the grid are four horseshoes that must each be placed around one of the four circle "posts" around the grid (those in boxes 1,3,7,9).
The center circle post will take one of the four choices.
Horseshoes may rotate, but not reflect.
Empty cells in horseshoes may be filled with any digit, including givens in the grid. Given digits in horseshoes may overlap with the same given digits in the grid.

Links
SudokuPad Link