Look through the threads, there is loads of information on air con.  I used the Roda in house system,  it has been a pain free experience and the system works very well,  however you will pay more,  how much more ?  Some of our fellow owners have claimed  savings  of 1k ? ..   Then you have to look at the specification and compatability of the units.  also don't forget that you will require some kind of servicing and  maintenance package . 
Regards Paul