Upgrading Toastman firmware on my Asus N-16

I have configured the hell out of my N16 with portforwards, static IP's etc etc..

My current version is:
1.28.7501 MIPSR2Toastman-RT K26 USB VPN

I want to upgrade to:
tomato-K26USB-1.28.0503.6MIPSR2Toastman-RT-N-VLAN-VPN-NOCAT.trx
(or if someone could suggest a better more recent stable firmware)

Will the later firmware be compatible with my settings backup? or can I just use the firmware upgrade feature & retain all my settings??

Thankyou