Sorry I didn't read the whole post but at least, I read a little related to ICS gun. Just cut out of the some crap, let me give you some light.
If you plan to get the ICS M4, you shouldn't get the half breed version. There is a review from our former ICS user and might be the person who has a lots of knowledge for ICS M4. The halfbreed version half the half clear receiver so because of that, quick swap the upper receiver is very limit sine the clear lower receiver tend to break down if you use so much force to pull the rear pin to open it up. So quick swap won't happen so quick anymore, beside that. Everything seem to be fine from my point view.
Since you are already AV, just stay calm down and waiting for a few ICS M4 full metal pop up. I wait for mine for almost a year until a brand new one pop up and least that 500 $.
Most of people turn to ask most of noob go to Classic Army or Upgrade TM because of their durability but the point is person who encourage noob to choose those brand is because they never get a hand on ICS M4 or work on internal of the gun, that's why ICS is way too off from their list.
The reason that I always suggest ICS to noob is because of their quick swap upper receiver than can go variety from 350 to 400 fps for outdoor and indoor, that's mean you don't need two rifle or go to gun doc and ask them swap spring for you or go www.mechbox.com
and learn to do. If you success then it's good for you but if not, you will end up bring to gun doc again, bring the whole gun to fix is way cheaper than bring the piece.
From my point view, ICS gun is like to dream to work with. It could has some issue with external but most the issue are easily to fix and noob can do it by themself.
Keep in mind that most of people say that ICS M4 is different design than of M4 user because of their swap upper receiver but there are a few parts that are different, Let me give you a list :
-Air nozzle longer than regular M4 nozzle,
-Anti Reversal latch is different design, regular M4 won't fit on
-Hop up unit is unique design like G36 but G36 and M4 won't fit, you can modify one piece M4 hop up to fit but stick with the stock one is better.
-Regular M4 grip, won't on ICS M4 as well except the guarder version is fit
-Stock, if you are willing to change stock then need to change buffer tube as well since ICS buffer tube slightly bigger than normal M4 buffer tube and need some modification as well.
-Old Model ICS M4 were using metric thread on their front set and new version is suing imperial thread so you don't have any problem to fit any front set except you need to sand a pin coming from the chamer not to get in with a new front set.
So far, the rest are regular M4 compatible, and also the rest internal are V2 mechbox.
Note : if you willing to upgrade gears on ICS M4 then you need to change the motor as well since the gears and motor of ICS are way deeper than normal motor and gear so regular motor won't turn the gears or you can just pull out the opinion of ICS Motor and put on a new motor.
Hope it hlep you make up your mind.