1) Not a very good idea to compare MEPIS
'betas' with 'released' versions of linux
2) MEPIS betas are for 'testers' not 'users'.
Whenever you test a 'beta' you should be more prepared for failures than to be expecting a beta to be as good as a released version.
If you want a stable version then use 6.0 with the ubuntu repos or 3.4.3 with the debian repos
Beta 6 has a bug so internet was not enabled when you install. All you need to do is go to kmenu/system/MEPIS/MEPIS Network Assistant. Go to the interfaces tab and check all of the boxes. Click apply, click ok and internet is back.
If you insist on using betas then you must report your troubles to
dev@mepis.org with a brief description of what is happening along with a description of your CPU size and brand, ram, drives, etc.
If you really want to help then try and run the app that is giving you trouble in konsole. If it fails there may an output in konsole that you can copy and paste into your email to dev.
That is how the bugs get fixed. The developers aren't telepaths. At least I haven't heard that but who really knows?
And lastly if you do test a beta and would like it upgraded to beta seven and beyond then you have to take all of the upgrades that apt-notify tells you to take.
Apt-notify is a yellow box that lives on your main panel, that may have a zero or some number under it. A zero means nothing to update now and a number means there is. If there are some upgrades to take from apt-notify then just left click the apt-notify icon and it will open synaptic. When you get synaptic open just left click the 'Mark all upgrades' button, go through the upgrade process and you will get the upgrades that you need to keep building your beta up to the final. You have to take them all.
DON'T ever open synaptic, hit the re-load button, then hit the mark all upgrades button when you are testing a beta or you will break it for sure.
Another really good place to get help with MEPIS if you get stuck is mepislovers.org It's a good friendly site with a lot of knowledge. This site looks great. I like it.