So I ordered Mongoose Traveller ...

[Brandon C]

No separate re-enlistment roll - promotion aka advancement handles that.
Task system - not the DGP one, either, so neither your 2300 nor MT nor DGP-CT experience will help with it.

Most of my CT gaming was befire I bought anything by DGP and I only used MT for one gampaign, do I used 2d6 plus mods for 8+ far more often than any of the task systems.

Armor reduces damage.

I'm almost going to miss the armor vs weapon to-hit matrix. Almost

End always gets hit first. So, now, low End is a glass jaw.

Many careers require survival rulls against End, so most combat-oriented characters will not have a low score, except possibly for aging effects or that silly injury table.

New Psionics rules.

Although they do seem to generally feel the same overall.

New Skill List.

Yeah, this is actually a mixed bag. More skills than CT, but some returning skills are renamed for no really good reason.

In other words, it's a whole new game

Nah, after first reading seems pretty similar. Probably less jarring than going from D&D to AD&D back in the day.