The .46 LA will power a 6.5lb Decathlon in a nice, scale manner. It might be a little tame for highly aerobatic flying, however. If one of the "tigre" engines that your local hobby store carries is the Super Tigre G-51 Ring, that would be an excellent alternative to the .46 LA. The Super Tigre G-51 Ring engine will provide much more power and can swing a bigger prop than the .46 LA; the two engines normally sell for about the same price.
The best deal on the planet right now for a 2.4Ghz radio system is the Airtronics RDS8000.
http://www.hobbypeople.net/gallery/751700.asp
http://www.amainhobbies.com/product_...tem-TX-RX-Only
An eight channel frequency hopping computer radio system with 10-model memory and advanced mixing and programming capabilities for aircraft, gliders, and helicopters all for $139.99 or $149.99 is a crazy stupid good deal. Add in the fact that the RDS8000 has been on the market for more than eighteen months without any systematic reliability problems of any kind and you have a surefire winner.
Airtronics has just started shipping its new 92664 RX60 6-channel park flyer receiver to round out it's receiver line:
http://www.hobbypeople.net/gallery/468516.asp
The 7-channel full range 92674 RX700 and 8-channel full range 92824 receivers offer a nice variety of flexible, compatible receiver choices. With the 8-channel 92824 readily available for $65, you don't have to take out a second mortgage or settle for an entry level receiver in order to convert your existing fleet of airplanes:
http://www.heliproz.com/prodinfo.asp?number=125342
Proven reliable and shockingly affordable, the RDS8000 by Airtronics is simply the best value on the planet. The radio ergonomics are also excellent; the RDS8000 is lightweight and is very comfortable in my hands.
Major reviews are available here at RC Universe, RC Groups, and at the AMA Sport Aviator website:
http://www.rcuniverse.com/magazine/a...article_id=995
http://www.masportaviator.com/ah.asp?CatID=3&ID=225
http://www.rcgroups.com/forums/showthread.php?t=802553
You can spend more money, but you can't buy a better radio system.
You don't have to spend a lot to get a great engine for your Decathlon or to get a great 2.4Ghz radio system.