I would like to suggest an 'Other' option for GOP and Dem primaries.
Currently to bet on 'Other', I have to short every contract, which is unwieldy. Shorting a contract at 5c means spending 95c. Thanks to linked markets, this is virtually free... except that I quickly hit the $850 cap, despite not having anywhere close to $850 risked in the market.
An 'Other' option would make things marvelously simple and clear.