I'm a tad concerned - not yet got Mavericks.
Some years ago I had Gmail downloading to my MacBook [ to sure if it was the MB or the MBP :( ] and it totally fouled things up - filled my hard drive in minutes flat. Went into Apple and after a while they were unable to really deal with it - so kept that for use on the Web.
Why am I worried now - NTL/Virgin uses the Gmail interface thingy so I hope it doesn't mess things up for me WHEN I decide to grab Mavericks. I'm used to MacMail and don't want to try something else.
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If a thing ain't broke --- DON'T FIX IT
Experienced in making a mess of things

MacBook Pro on OSX 10.8.4 ,Virgin Super Hub , [ sssh - and a PC wired lappy using XP Pro ] all on
Virginmedia 60meg