Logic Masters Deutschland e.V.

Today we have puzzle created for Scojo's prompt, as redeemed by isamook, to create a puzzle with a single grid and multiple solutions :-)
I estimate difficulty to be 3*, however I have decided to post it as 2* according to testers' feedback.
I hope you will enjoy and I would be really grateful for all the comments and ratings.

Normal sudoku rules apply.

Region whisper: Choose whether you want turquoise line to be a German whisper line or a region sum line:

German whisper: Neighbouring digits along a line have a difference of at least 5.

Region sum: Box borders divide a line into segments which have the same sum.

Remaining constraints are standard:

Antiking: Identical digits cannot appear in cells a chess king’s move apart.

Little killer: A clue outside the grid gives the sum of the digits along the indicated diagonal.

Diagonal: Digits along the marked blue diagonals must not repeat.

Renban: Digits along a purple line form a set of non-repeating consecutive digits in any order.

Thermometer: Digits along a gray thermometer increase from bulb to tip.

Quadruples: Digits in a circle must appear within the four surrounding cells.

Killer: Digits in a cage sum to the total given.

Black kropki dots: Digits in cells joined by a black dot are in a 1:2 ratio (i.e., one digit will be double the other). Not all dots are given.

X: Digits in cells joined by an X sum to 10. Not all Xs are given.

Maximum: Digit in a cell with a greater-than sign pointing inwards is greater than all digits in orthogonally adjacent cells.

Minimum: Digit in a cell with a less-than sign pointing inwards is smaller than all digits in orthogonally adjacent cells.

Choose how you want to solve:
Both without solution check: SudokuPad Link
German Whisper with solution check: SudokuPad Link
Region Sum with solution check: SudokuPad Link