Thank you for your post. This is what lead me to the RF Engine. I really think other arduino users would like these. Especially if they do a side by side comparison between XBees. This biggest downside to me is they are only available at future electronics. There are too many good points and advantages to list.
Price wise:
The lowest power module is $24 right now. http://www.futureelectronics.com/en/technologies/semiconductors/wireless-rf/rf-modules-solutions/802154-zigbee/Pages/2270387-RF100P86.aspx
The amplified version with an F antenna is $35 right now. http://www.futureelectronics.com/en/technologies/semiconductors/wireless-rf/rf-modules-solutions/802154-zigbee/Pages/6691737-RF100PC6.aspx
Then the amplified version with an RP-SMA connection is $39 right now. http://www.futureelectronics.com/en/technologies/semiconductors/wireless-rf/rf-modules-solutions/802154-zigbee/Pages/7782840-RF100PD6.aspx
For comparison the xbee pro rp-sma is $44.95 at sparkfun. XBee Pro 50mW Series 2.5 RPSMA - WRL-08768 - SparkFun Electronics
I used to use an arduino/Xbee combination everywhere I needed wireless data. Now I can just put a SNAP RF Engine in some of those places without the arduino. It is nice to reprogram the RF Engines over the air.
For some reason, the arduino community does not seem very interested in the RF Engines. They have filled a need for me. They have also created some needs for me. I couldn't find a cheap breakout board. So I made one. It is what pushed me to learn eagle and make my first PCB. (for anyone interested http://www.jcwoltz.com/2010/10/synapse-breakout-boards-available-for-sale/)
Beyond that, I needed to run RF Engines from a rechargeable battery. I have made a PCB with another guy, Serge Sozonoff begin_of_the_skype_highlighting end_of_the_skype_highlighting begin_of_the_skype_highlighting end_of_the_skype_highlighting, to charge LIPO batteries from a solar panel. An image:
The detail of the first batch are at: http://www.jcwoltz.com/2010/11/pcbs-back-and-next-steps/
The details haven't been written up, but the latest board:
All these designs and more are released under a CC BY-SA at: Google Code Archive - Long-term storage for Google Code Project Hosting.
If someone wants an arduino shield, I have started one. They could either ask to have some made, or take the design and make their own. An image:
I'm sorry for repeating some of this information. The RF Engines have allowed me to do what needs to be done quickly. I have done some basic testing and I'm able to reprogram an arduino wirelessly using RF Engines.