The short answer is no, I've never used Arduino. If you have never worked with embedded electronics, Arduino is a great place to start. Arduino will get you into both the hardware and software side of things without having to get too far down into the nuts and bolts of a particular MCU (microcontroller unit). But they are way too expensive if you plan on going to full production to make money.
The long answer.
My very first rapidfire modchip was built using a development kit from Atmel (
http://www.atmel.com), a popular name in MCU (microcontroller units). At the time, Atmel didn't have a lot of lower-power MCU's, which are needed since the Microsoft circuit boards operate in the 2.4-3.0 volt range, so I ended up changing over to a Microchip MCU (
http://www.microchip.com) After a lot of planning ahead, I selected the Microchip PIC24FJ256GB110 MCU for the macro controller modchip. That MCU had all the features I thought I'd need to make the macro project a reality. Usually for each new project, I just design my own development PCB from scratch using EagleCAD (
http://www.cadsoftusa.com). But I've also used pre-built development boards over the years to help me get familiar with each new family of MCU that I use. For your reference, here are some development boards that I have collected over the years from various projects:
http://www.olimex.com/dev/avr-usb-162.html
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en536385
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=1406&dDocName=en535092
These development boards cost anywhere from $30-$100. Hardware-wise, these development boards are very similar (if not superior in the case of the PIC24F starter kit) to Arduino. Companies like Microchip and Atmel provide free software frameworks for just about anything you can think of. These free frameworks are very powerful, but, they are also all very very complicated.
The advantages of Arduino are ease of use, low learning curve, and a variety of "plug and play" Arduino "shields" offered by third-party vendors. For example, if you want to start a new GPS (global positioning satellite) project, you can buy nearly any Arduino and an Arduino GPS Shield and probably get a working GPS project up and running in a weekend. Want to work with an LCD display? Just buy an Arduino LCD Display "Shield". You can stack up a bunch of these third-party "shields" and pretty quickly get a working project up-and-running without needing to know much more than a little C programming language (or whatever language Arduino calls their language, I can't remember what they call it).
Negatives or Arduino are high cost, hardware and software limitations (some may disagree with me here, but I don't believe Arduino environment is sufficient for serious projects). I feel that Arduino is not as powerful as building a project from scratch. Arduino is basically an organization who created an operating system that runs on some Atmel MCU's. Their system is great if you are a hobbiest, or someone new to embedded systems, that doesn't plan on going to commercial production with your design. I don't think Arduino is necessarily not-for-profit, but you'd have to check their website to get the details.
Anyway, I think I've about rambled enough on the topic. If this is your first embedded systems project, I'd start with Arduino, but don't be disappointed if you feel that the system has too many limitations to accomplish what you want to do. It's a great place to start. When you are doing this kind of work, you're going to find that you don't get it right the first... second.. third.. fourth... or fifth try. But it's a lot of fun!!! Once you've completed your first project, you will be addicted.