After reading up I opted to replace with same turbo, mostly cause i do not understand enough about various tuning/compatiblity points and work needed to adapt a different turbo and having then to tune it/remap etc. to account for later/earlier spooling etc etc. figured I do not have facilities or know how to risk making it work.
Easiest option would probably be to send old turbo for a rebuild and hybrid upgrade to say turbo dynamics etc. from what I understand anyways.
Having had some talk with a tuning garage there is not a lot of modifications that are available for ATL engine either and fitting a 1.9TDI PD is a better choice which from what I read Germans are quite familiar with.
Anyways, long story short figured it is not worth the hassle pushing engine beyond what it is comfortable with with turbo/injectors, as while it can be pushed gearbox/clutch will suffer even if block is capable.
Will probably give it a go when i have space for another car to use and i can afford to have my A2 worked on for months to fit a 1.9 in there, cause I like suffering I suppose.