Hi, I'm interested in the SZ series and was wondering whether to get the SZ720FM or the SZ520, has anyone played these and know the difference or can anyone tell me if these are good axes.

They're both pretty much the same.

The only difference is cosmetics, 520 has quilt top and 720 has flame top and body/head binding.

Both would play and sound the same. I haven't tried the SZ but i've heard they're good.
Great guitar, good sustain, pretty much everything. Do try it 1st, you may/may not feel comfortable with the neck.

No difference between those 2 accept cosmetics and finishes
"Play with your ears" - Yngwie Malmsteen, Paul Gilbert
Thats what she said...
i seem to remember them having a pretty thick neck, so keep that in mind...you should probably try one out.