Hi Trung,
A thread like this is no doubt going to give you a thousand different responses so here's my 2c.
My first scope was a 4SE. Very easy to use and very portable. Very much designed for the beginner. Having said that, the mount with a few mods is now driving my Astrophotography gear lol. You will be able to see Mars, Jupiter and Saturn with it quite well but not with the included eyepiece. The moon looks pretty good through it too. You can make out some of the larger star clusters and a couple of the brightest nebulea like Orions nebula but that is about it.
The one thing I think everyone needs to remember when answering this post is that you live in Melbourne metro. Yes a dob or lower f ratio refractor will capture more light but that includes light pollution. As you mentioned in your original post, you're going to have to take which ever scope you get to a darker place to get the most out of it.
I'll now let all the others have their say but all I will say is welcome to this amazing hobby.
