I think you'd be better off with the Fantom X7,for more than just the price.
G70 is a whopping $3967 approx.
X7 is $2495 at Sweetwater.
G70 has one SRX slot
X7 has FOUR SRX slots
Now,if you're going to use your second KB as a live rig more than anything else(ie sampling,sequencing) then you could save a TON of $$$ THIS way:
http://www.ke-musik.dk/Upload/HtmlArticles/Article1284/index.htm Scroll down to "demoer mp3".
Specs on EXR7s(All EXR's sound the same,more or less)
http://www.sweetwater.com/store/detail/EXR7s/ Sequencer on the EXR7s is not worth a crap,but the sounds are really good!
BUT if you still might need a sequencer after all(but not sampling),then:
http://www.sweetwater.com/store/detail/JunoG/ Only bummer here is that you get cut down to 61 keys,but you don't pay 4 grand for just one SRX slot,you pay far less!
I hope this is a good starting point and I hope you find what you need.