144hz vs 240hz or 300hz is it very noticeable? - YMMV, once you are at 120+Hz, it comes down to how competitive you are, it's nice but once you've reached 120/144Hz, it's all icing IMO, and the panel quality (colours, response time etc) are more important.
The 2080 Super Max Q Vs 2080 Super full fat seems a huge gap in performance looking across the web is that right? - Yes correct, the MaxQ has about half the power allowed the Super MaxP does, which heavily restricts the clocks. The Super and non Super 2080 Max Ps are 150W+, vs 70-90W on MaxQ.
lastly I currently have a MSI Titan laptop with a 1080 card 4 years old. Is there a massive jump vs the 2080 super Max Q - I would say not enough for the outlay. There's a jump and extra features, but Pascal 1080 Max P was pretty decent, you'd notice a substantial difference with Max P 2080, but not convinced by MaxQ which is designed more for power saving/thinner and lighter than performance, and performance sometimes really tumbles because of that. I am assuming the Titan had a MaxP variant though, if the thing had a Max Q then it may be a more substantial uplift.
As it is the 2080 Super Max P for laptops is essentially the same as the original 2080 Max P for laptops, but with a boosted TDP, to my knowledge, the lower SKUs (2060/2070) got more tweaking.