I strongly suggest staged. I found we had to roll one of our 6.1.5 builds back when upgrading directly to 7.2.1.
In fact, I think it's still back at 6.1.5 version. The config file is different, the click to actions didn't work, we were unable to log in, and although I then used the install version with the config file merged, it was ugly.
However, I know I've upgraded quite a few sites without issue, but they were in stages.
There are some quirks with jquery and skins that may need to be looked at as well as rearranging of the default.css file, the css code and other things that make one think - never do an upgrade when you're about to go to bed, unless you have in mind that you don't need to sleep that night.
Just my two cents.
Nina Meiers
// edited - I meant 6.1.5 not 6.1.2 which was originally written.
Nina Meiers My Little Website
If it's on DNN, I fix, build, deploy, support,skin, host, design, consult, implement, integrate and done since 2003.
Who am I? Just a city chic, having a crack at organic berry farming.. and creating awesome websites.