Ah, ok, you have a communal cold roof space cistern, quite high above you is it? Any idea roughly in M? To give a guide measure the height of your room times how many are above till getting to the cistern in the roof.
A combi will always struggle, it just in their nature. You will certainly get one good shower, that's for sure but even then it will drop if you use another HW outlet, it's their one major drawback.
You can certainly lose the mexico and put a wall mounted boiler in, how that's to be used is another question. It really needs a close look at what you want, what you think will be acceptable and from there what would be the best model to achieve that. 10L/min is all fine and well but if your cold mains can't delivery that dynamically then you'll struggle, pressure is a key factor to that and that is all centered around what your mains can deliver.
A combi will always struggle, it just in their nature. You will certainly get one good shower, that's for sure but even then it will drop if you use another HW outlet, it's their one major drawback.
You can certainly lose the mexico and put a wall mounted boiler in, how that's to be used is another question. It really needs a close look at what you want, what you think will be acceptable and from there what would be the best model to achieve that. 10L/min is all fine and well but if your cold mains can't delivery that dynamically then you'll struggle, pressure is a key factor to that and that is all centered around what your mains can deliver.