debian stable, now i want to remove debian main and install debian lmde,
Well, my suggestion is No, do not remove a stable Debian.
Let it be in the hard disk, if you must try Debian testing, a high chance you will need this also
Just install Debian testing onto another partition and play with it
but now with the update packs, is it stable enough for a intermediate user?
I hate to answer this, but then I felt I just want to answer
in different ways
I have a few computers, I multi boot lots of them and run Debian Sid, LMDE, LMDE turn to Debian Sid, etc. LMDE , inspite of tracking Testing, had more breakages, a few cases of pulseaudio not cooperating..and I have to remove Pulse and replace by alsa to get sound working. This does not occur to many other partitions and distros.
i know the command line, but i really dont know how to fix possible regressions and breakages.
My suggestion is, to repeat, do not remove your Debian Stable, you will need it at time, to use ( not to play) your computer, and to use it to repair another partition that is broken
When you start your Debian Testing or LMDE-testing adventure, try to also learn how to clone the partition, and how to reinstall from clone. Once you get into this system of clone and reinstall, you can be quite sure you can return to the last working partition and thus learn from there why it breaks and attempt to repair.
Subscribe to a few threads that are related to breakages, you would see what other people did to rescue some breakages , some of them even tracking Debian unstable..
EDIT, just suddenly want to add one point.
Don't be afraid to break, haha, that is the way I learned too.
I recalled when I started to play with Sid, on terminal, I saw sid wants to remove 500 packages out of 800 installed,, and guess what, I went ahead and get the biggest oop!! the update remove all of my KDE desktop, but then guess what, I had a working Debian fluxbox!!
When Debian is run from fluxbox I can install another DE again and it recoverred.
That was when I appreciated those old advices about how to respect the system.
That advice was 'pay attention to what Sid wants to remove'...
another advice was ' install apt-listbugs' , that was not done till I broke one partition..
So in simple term, do not be afraid of breakages, but must learn from it so you can appreciate much more on simple, trusted advices ( lots of them around, but need to find them
Good luck to your adventure, just need to fasten safety belt..