You'll get much better than 10MB savings, first. And APE isn't that much better than FLAC either. See
comparison page for details. (and don't start about how it's biased; Monkey's Audio has the same chart at their site) MA, at 'normal' setting, took 13:27.96 seconds to encode a 14-track CD, resulting in a 393.17MB file. (from an original size of 780.56MB) FLAC, at -5 (normal, and BTW, don't go above normal on any lossless encoder. The size difference really isn't worth the time) took 12:54.19, resulting in a 413.46 MB file. That's a 38.29MB size difference, and a 121.95 seconds time difference. But what's particularly telling is the decode times. 14:31.90 for Monkey's Audio, 7:08.80 for FLAC. That's more than twice as fast. This is why FLAC has been implemented in portable devices; as it's fast enough for the relatively puny CPUs in those to decode them in real time. Also, of course, FLAC is GPL'd, which is less restrictive than MA's open source model.
So, in the end, you just have to decide what you like. I myself like FLAC, for it's fast decode time (I do a lot of lossy codec testing, where I have to decode entire albums), GPL licensing, and it's better multi-platform support.
Oh yeah, these encode/decode times were tested with a PII-333 with 256MB of RAM, running WinNT 4.0 SP5.
(-:Stephonovich:-)