Personally, I would keep the Airtronics Radio, although I agree, I would have gone with the RDS8000 too! It must be the SD5G, great radio, probably wont outgrow it for a long time!   You say that you already can fly a 3 ch plane fairly proficiently, T/O, Landings, Loops, etc.  If you can do that already with a 3 ch plane, You shouldn't have much problems flying the TT 40 MKII..  you can use the Pass the Tx method of training, have the instructor get you 3 - 4 mistakes high and have him give you the Tx, if you get into much trouble, pass the tx back to him, to recover..  that's how I learned with a Sig Kadet MKII (Very Similar to the TT 40 mkII) over 25 years ago.. 

otherwise, you have a great setup, enjoy it!

Craig.