Question on going massive.

Another poster on the ePMP explained to me a little on the Medusa. I currently have deployed the ePMP 1000 with force 180-200's. We always keep extra AP's because we are in AZ and lightning is what it is. I am tossing the idea of investing in the new Medusa AP's as a backup for the next time I am forced to crawl up and replace. My question is, if I do can I use the current subscriber units for my customers and offer the 450 SM's to customers that want more BW (and are willing to pay). this may have been asked before, if so just ppoint me to the convo. 

The PMP 450m only interoperates with 450 platform hardware.  It will not communicate with ePMP subscribers.

I would suggest starting with a 450i sector, and filling in with 450 subscribers.  The 450 subscribers will work using the current system, then, if additional capacity is needed, simply change AP hardware.