I have been configuring Dynamic VPN on my SRX 210 device, since I didn't have Steel Belted Radius server and had to use a free radius server. Therefore I tried freeradius server which didnt work for me. I then installed TekRadius server which is also a free software and worked perfectly fine.
I faced loads of difficulties while configuring this radius thing for dynamic vpn. On netscreen, it was pretty much easy to configure dialup vpn.