Definitely, Mavericks behaviour is different with 8GB vs 4GB, with 8GB it will be much more free in letting apps stay in RAM, just because it is available (I have a 4GB MBA and 8GB cMBP both running Mavericks to compare).
For sure Mavericks is delaying using compressed RAM here, simply because real RAM is available.
Out of interest I have a clone of the OS and Apps on the MBA, the only difference is the MBA is 4GB and 64GB flash vs the cMBP 8GB and 120GB SSD and 1TB HDD.
If I load up with Aperture, Word, Excel and Powerpoint, plus my 3 daughters accounts are logged in with iTunes and Safari on each then I get virtual memory up to 7GB, approx 1GB swap (mainly from having multiple accounts logged in I suspect - see screenshot of the activity monitor memory tab below - note pressure is still green).
No admitedly swapping will be out to the flash storage but I have to say the machine is just as responsive as the cMBP I have with 8GB and an SSD so in the real world, for most users, 4GB and Mavericks can give a very 8GB-esque experience without difficulty...
If I was to buy a new machine today I would only be concerned about 8GB on an HDD-only machine as swapping will take longer, on a Flash or SSD machine I wouldn't be concerned at all - and certainly there is very little justification for 16GB except for specialist applications, essentially OSX Mavericks and beyond will future-proof memory for you.