If you use Packer, just go far the 'shrink variables' option and gzip the resulting code. The base62 option is only for if your server cannot send gzipped files. Packer with 'shrink vars' achieves better compression the YUI, but can introduce bugs if you've skipped a semicolon somewhere.
base62 is basically a poor man's gzip, which is why gzipping base62-ed code gives you bigger files than gzipping shrink-var-ed code.