ChipKIT is an excellent substitution board to Arduino. It offers better performance as it is based on PIC32MX320F128 microcontroller based on 32-bit architecture. The microcontroller has 128K of Flash and 16K of SRAM onboard. Having Arduino Uno shape factor ChipKIT offers more 42 programmable pins. ChipKIT like Arduino can be programmed with a bootloader that communicates to PC through USB-to-USART converter chip FT232RQ. Digilent has developed an STK500v2 based bootloader that works on PIC, so it is easy to program using AVRDUDE tool. Besides that, they adapted an Arduino environment to work with ChipKIT boards. It’s called Mpide. It also supports Arduino boards, but it aims to program ChipKIT boards. Programming experience is pretty same as for Arduino, and even most of the examples written for Arduino work on ChipKIT. This is true since there is no specific hardware elements touched like program memory or EEPROM. As you know Arduino is rich in hardware support libraries as all shields are designed for Arduino. Latecomers like ChipKIT even if they are hardware compatible may have some difficulties with library integration due to the different architecture.