I agree with Fred.. Go software, but keep your EX-5! That is a powerful synth.... I used to own it's little brother the EX-7 and I'm still kicking myself in the ass for getting rid of it.. That EX-5 is a powerhouse and it's sounds are awsome! A good upgrade from the EX-5 (if you decided to get another workstation) would be the Motif...
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GEAR: Yamaha MOXF-6, Casio MZX-500, Roland Juno-Di, M-Audio Venom, Roland RS-70, Yamaha PSR S700, M-Audio Axiom Pro-61 (Midi Controller). SOFTWARE: Mixcraft-7, PowerTracks Pro Audio 2013, Beat Thang Virtual, Dimension Le.