there shouldn't be any problems. if you want to be perfectly safe, then you might want to recompile the MySQL package on the 7.1 system. i seriously don't see any problem just copying the files tho. the main difference between upgrades on distros are usually just new kernels and slightly tweaked install and boot scripts. the meat is 99% the same.
all this is, of course, assuming that you're using the same processor architecture on both the 61. and 7.1... (just making sure