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I think freedom to choose who you fight with or against is one the more intrigueing aspects of multi player chess, and extra constructs should be avoided where possible.

Reward systems for enterprising players seem necessary-gaining players you captured, and in the event of checkmate inheriting the remaining piece set.

Incomplete information is a good feature to add. Personally I think the mechanic of Dark Chess, where a player can only see through his pieces, is more ideal as it again rewards an agressive player, in a game system where conservatism could get unfairly rewarded. 

Simultaneous move commit is intriguing in itself and easier to implement. Is there a chess variant based on this mechanic?

It obviously requires some exception handling, for example;

*Non attacks*

If a piece moves to retaliate, but a piece isn't actually captured it captures its own piece/or produces a null move. Only allowed if a piece is actually threatened.

*Pawns misses*

If a pawn attempts to capture on a vacated square, it moves straight forward. If it can't advance it produces a null move.

Material wise pawns probably have to replaced by something more mobile.