HP Z3100 With 3rd Party Inks

Hi there
This is my first post on Luminous Landscape, I am a Landscape photographer operating in Austria, and print large 44" prints of my work. I work with medium format 6x6 and 6x17 and print up to 1x1Meter or 1 x 3 meter exhibition prints. Print quality is really important to me and so is the reliability and quality of the gear I use.
I currently have the Epson Pro 9600 which I use for the big print work. I have found that running the machine on Pigments from a third party firm I have found, produces better quality repro than that from Epsons own inks. Not only that but they come in at a fraction of the price.
I am frankly sick of repairing this machine endlessly, because of issues with a blocked head or clogged dampers. I have replaced the head in this machine for the fourth time in three years. Before anyone says it must be the ink, the first two heads where with Epsons own inksets. This for me is just an unexceptible situation, costing money in endless head cleans and parts that have to be shipped from Germany.
So I am looking for a new machine. What to buy is the burning question.
my list is:
1)HP Z3100
2)Canon ipf 8000 or an 8100
3)Epson Pro 9800 or 9880

I print mainly on Hahnemühle art papers and on Breathing colour brlliant white canvas. So the media is pretty heavy and ink thirsty . I understand that Epson have pressurized their new ink cartridges which i guess means will be problematic to use third party ink. Plus there is the issue on the Epson of not being able to print on gloss media without having to drain down the Matt Black channel. Which wouldn´t be so bad if the cassette sucked the ink back up before changing over, but it doesn´t.
Then there is the issue of what happens when you get a clogged head.
So for me the Hp and the Canon seem to look more attractive.
What I don´t know and would like to throw out to you all is;
Do the other two systems (HP and Canon) run on pressurized cassettes? and can you use third party inks with them?
Does the Canon also have a user changeable head, and if so at what sort of price.
And what is the difference between the the various Z3100 machines? ie: Z3100, Z3100ps GP, and the Z3100GP.
And is the profiler in the standard machine any good? and if so why is there an optional device?
So I guess thats about it. I would love to hear comment from anyone that has one of these machines and prints on similar media, and what they reckon.
Thanks for taking the time to read this.
regards
Andy