I have just started using the DevArt MySQL connector, and so far this is good. One of the problems I discovered is that it does not seem to offer an equivalent of type MySqlDateTime. This means that the timestamps must be mapped to the DateTime.NET type, and the consequence is that the timestamp "zero" cannot be represented as such and is converted to 01-01-0001 on the .NET side.
Something else you should be aware of is that the MySQL (non-DevArt) connector is GPL, so if you want to use it from an application without an open source, you must apply for special permission. This was doable when Sun was owned by MySQL, but now the process looks more complex than Oracle. You must first register as an Oracle partner, and their website offers Gold membership to integrate with the driver, which costs $ 2,500 per year. It is unclear whether this is mandatory and whether your application will be reviewed with free membership. I was also unable to use the registration page of my partners - it seems to be broken, and they did not respond to the request that I sent them. In short, $ 100 or so looks really cheap for a DevArt connector.
6 month update : DevArt connector works well and I continue to recommend it. And Oracle confirmed to me that they needed $ 2,500 a year to allow their MySQL driver to be used using open source software.