The only real difference is more power and different ergonomics, so it may or may not be more comfortable to use. If you want one machine to do it all get a GG6 or a Flex. The GG6 has already proven itself on the market to be a great machine and it has a lifetime warranty. The Flex is a awesome machine and it will correct paint noticeably faster then your PC.
Then there is the option of the Rupes polisher which is another great machine, I've been using a friends 15 lately and have to say that I didn't really care for them in the past but the more I use em the more I like them. They correct fast and run smooth, but if you are going to have one machine the flex is more versatile with pad sizes and backing plate sizes.