I see that many awesome software are not available on Manjaro. For example, Bomi video player should be in Manjaro repository. Persepolis download manager and XDM should also be in repo. These software are available in Arch repository but I am hesitent to install from their as it may crash my system because Arch repos and Manjaro repos are different.
It's not in the Arch repos but in the AUR. Manjaro is compatible with the AUR (its package manager Pamac even has built-in support for the AUR!). So, go ahead and install the AUR package!
So there will be no dependency issues. I had this problem with another distro where installing software from third party repo broke my system because it installed a newer version of software not compatible with my system. Actually that is what I am afraid of. Will things like that happen to my system if I use AUR? If such things will not happen to me, then I'll install.
Manjaro and Arch are different regarding kernels and video drivers, so go ahead with AUR, I'm currently using a lot of AUR programs
There is a "conflicts" array in each package. If a dependency package from the AUR is already installed on your machine from the main repo (in a different version), the package manager will tell you that there is a conflict and ask if you really want to substitute the already installed package with the new one (the default setting being to keep the old package). So, unless you don't read what the package manager tells you, everything should be fine!
I went on for installation of one package and this message came up.
> ( Unsupported package: Potentially dangerous ! )
That's because the AUR means "Arch User Repository" and the packages there are created by users. So, basically, you could register an account in the AUR and upload a package which is completely messed up, without the Arch developers even noticing. Or, even worse, you could put in a package including malware or a virus. That's why there is this warning. But in reality (at least in my experience) the packages are pretty good, the only problem being that maintainers sometimes forget to update them in time (for example if some library gets updated and the package needs a rebuild, it could happen that the program installed by the package doesn't work any more). But the worst case scenario is then that the particular AUR package stops working, it won't affect the rest of your system any further.
You probably should learn more about AUR. Read here
The AUR is not like a 'third party repo' in ubuntu. Please follow kainonergon's suggesiton and get familiar with it. You'll learn to love it (and the lack of ppa's ;-)). As for packages being add to manjaro repo's - this does happen sometimes ... but only for packages deemed important enough to adopt.
If the AUR package works on arch and is not related to kernel or graphic stack.. it should work on manjaro
There is maybe one thing that will not work... It's if an AUR package is updated because API change in the dependencies... You will have to postpone the update until those dependencies get updated on manjaro stable..
As if u update the package it may not work until the dependencies is on the right version.
ex: a plugin for kodi.. you may receive an update notification for an update of a plugin on AUR because kodi got updated from kodi 16 to kodi 17 (on arch) and because there was changes in the kodi plugin API. you may need to wait kodi 17 hit manjaro stable before to be ale to update the AUR plugin,