Nimbostratus
MVPill just state it again, contact you local F5 team or partner and if you dont trust your partner (something i find rather shocking) just contact some other F5 partners and compare their input and let them explain it.
20Gb bandwidth seems to be supported in other platforms also, pretty much everything from 8950 and up. not sure on prices, would have to check with your partner about that. the 2250 blade does 80 Gbps L7/L4 throughput according to the data sheet.
advanced routing module isnt a full module as LTM, GTM, ASM ... and can be included with LTM without a problem. as you state yourself you only need it when you plan to do dynamic routing, i.e. OSPF, BGP, ... if you dont need it dont buy it, you can include it later on, just add a license. the 2250 blade with handle LTM on itself more then fine.
as for EM / BIG IQ they will both handle the Viprion platform fine, BIG-IP is more the software side then the hardware side anyway. personally i wonder how useful it is with only a few devices, but that is up to you. you can always add it later.