Best practice migrate NSRP Active/Active to SRX Cluster?

Hi All,

If i have Netscreen cluster active/active and i want swap/migrate it with SRX cluster 5800, may i know whether i the best pratice is active/passive or active/active also. If i setup SRX cluster active/active then i need add new physical cable because as i'm undertand active/active on SRX will have RG2 or etc. The purpose is config one-to-one swap without need to change config on other equipment except the ISG to SRX. If i setup both SRX without cluster what the disadvantges except config not syng or have two devide need to manage. The protocol in the existing ISG is just static route only.

Thanks and appreciate some advise.