if you live somewhere that you are able to use Nokia Messaging (it's not officially available for all countries/operators, although you can get around that by temporarily swapping out the SIM for one from a supported country/operator) then you can set up gmail within your NM account and it works very well (in my experience) for push email. I have the native email client always open on my device (no memory/performance issues) and I get push mail instantly (often before it hits gmail on my desktop PC). This config covers 99% of my needs - for the other 1% I just log into gmail on the phone browser.
I believe that there can be problems if your gmail inbox becomes excessively large, but that is down to you to manage.