Note, the kickstarter phase of digispark has closed 3 days ago. They do plan on offering digisparks for sale after the initial kickstarter pledges are sent out. At the moment, they are talking about general availability in December, but I've had some kickstarter campaigns that were 9 months late in delivering their rewards. There is the tweensy 3.0 that ends in 2 days, that will have 3 separate UARTs and is based on an Arm processor. While it will use similar libraries to that on the Arduino, it isn't and Arduino, and there may be some initial teething pains. I should mention that I have put money down for digisparks and tweensy.
If you are dealing with higher voltages, perhaps you want to use a Ruggeduino, which is better protected against high currents: http://ruggedcircuits.com/html/ruggeduino.html