For prototyping the BLE shield is the easiest and best option - applications can be built with no special mainboard considerations which means no IDE dependencies and the SDK provides a comprehensive API that makes working with the device a breeze. Debugging is also a breeze via the traditional debugging methods used for arduino.

If size is an issue then this wont be an option for you - a complete setup can be quite bulky in nature however you can provide between 5V and 20V of power to the mainboard which can make installing and deploying the device easier in some circumstances. The RedBearLabs version provides additional functionality and optionally an external antenna.

Since an arduino UNO is required at minimum, a complete working solution can be pricy.

The Blend Micro didn't skim down on connectability options as it still offers six analog, eleven GPIO and a few GND pins by clever placement along the edges of the board. With the integration of a micro USB connector debugging is just as easy as it has always been which is critical for development using the Serial Monitor.

It is a great size and can be powered by providing between 5V and 12V or via the USB connector; it unfortunately doesn't have the option of using a CR2032 battery even though it operates at 3.3V internally. Overall it provides great functionality in a small package - the best of the series of devices that were evaluated.

As a combined arduino and BLE micro controller - the pricing is good and worth it.

A custom SDK is provided and there is a dependency on the arduino IDE 1.5.7 beta due to the use of the ARM CPU - which is limited to thumb instructions so a number of built in libraries may not work (Scheduler for example) and the documentation is poorly written at best. If you dig around the header files you will however find a nice set of well defined APIs.

For prototyping and development a USB shield is a must however the team obviously didn't consider that using it on thin laptops would be cumbersome. Powering the device can be done by providing between 2.1V and 3.6V - conveniently a CR2032 battery shield is available but doing so loses the size benefit. However, if you are happy to perform some soldiering - then you can maintain the size advantage .

With a numerous kits available, the pricing is competitive and definitely worth considering.

An interesting feature is the ability to program the device wirelessly over BLE - however this comes with unfortunate side effects; currently you must have a relatively new Apple running Mac OSX 10.9.2 or newer. There is no security for flashing the device so it is easy to highjack - which means it will not be of much use for any security solutions. It uses a custom SDK that is very limited and has a crazy installation dependency on the arduino IDE 1.0.5 with Teensyduino extensions.

The lack of a USB connector also meant that debugging your BLE application is not so easy (as the unit can only connect to one device at a time). You could use the LED as a debugging tool - but only hardcore types would dare to do that. It requires between 3.0V and 3.6V to operate but the team was smart to provide a CR2032 battery slot on the underside.

With a few sensors integrated and the low price this one is cool but for fun projects only.

Overall; it really comes down to what you want to do with these kits to really decide which is best for your project. The Blend Micro and LightBlue Bean are strong and relatively close - but if security is a concern then the choice is going to be simple. I've had fun playing with all of these kits with the RC buggy hack (yes, I have gotten every kit to work with the project).

I hope that some of the feedback here is useful to assist in your purchase decisions!