Hello Joe,
I’m also rather new in this area.
But I will advice base on my experience.
As for your questions,
1) Can both set up handle 40d + grip+ 70-200 f2.8 (4kg load) weight with ease & firmly in place? Im worried about flexing even though the load is below the max load stated.
Yes, both able to take the load. You can check the specification on the marker website.
You can check with this link, there is a review using GT1541T with Q3T BH and mounted with a 5D with 100-400mm lens.
https://photography-on-the.net/forum/showthread.php?t=538298
GITZO GT1541T able to take the capacity weight of 8kg.
190PROCX3 able to take the capacity weight of 5kg. (But I felt able to take around 8kg too, due to the weight of the tripod)
http://www.gitzo.com …ryKey=1CAT:AAA1:2CAT:BB59
http://www.manfrotto.com …/16519?livid=68|69&idx=71
2) Do you think combi 1 is enough for newbie like me. or combi 2 will be a better purchase in view of long term?
That’s I can’t advice you is still depend on what you wants and your needs.
My personal feeling is both tripods are good. That why I didn't sell my 190PROCX3 after getting GT1541T.
If you wanted to have a light weight and compactness go for GITZO, their service and tripod quality is very good.
I felt GT1541T is very good for travelling due to the weight and compactness and easy to carry around.
Reason is I walk and hike a lot too. So for you I wanted to carry a light weight as possible.
As for 190CXPRO3 I use it for Macro shooting because of the centre column able to switch from Vertical to Horizontal position.
That makes is very useful for me.
If you don't really traveling or hiking a lot, you can always get a 190CXPRO3.
For 190PROCX3 the quality is not that great if you compare to GITZO tripod.
You just need to hold it and feel it and is very much different.
3) Apart from weight difference between the 2 tripod legs, in your opinion is it justifiable to pay for the price difference / quality difference?
That will depend if you have extra $$$ to spare to get it.
For me, will be look at the long term not short term. If not you will spend more $$$ at the end.
No matter what you got a tripod make full use of it.
is not will be waste of money. I see many ppl get a tripod (Normal Weight) at the end their tripod stay at home.
So is still depend on you.
Anyway, Happy shooting and have fun.