well, both is cool. ic610 is nicer looking vise and functionality. easy to use. its based on OA, i dont know what you wanna design, but u should have the latest version of the other programs like assura and etc. and also some vendors they have Design kits for OA.
IC5141 is older, use latest ISR to install and also most apps they are compatible.like mentor's Alink etc. and you can find more tech kits from more vendors for ic5141.
this is what i encountered in my work, so i stick to ic5141.
at end of the day you have to decide.
cheers