One point to remember about the Mk 11 or 17 is the spacing of the ports. If you want to use a hoseless dive computer you will need to use a MK 25 due to the greater spacing between the ports. I have several MK25’s and they are excellent regs. The parts program makes ownership more affordable as you only pay for the labor. This can be a significant saving over the life of the reg. There are Scubapro Dealers in Ireland, I just don’t know where.
Atomic regs are good also but slightly more expensive. There is no dealer for Atomic Aquatics listed for ROI/NI so the servicing may have to be done in the UK.
Take a look at the Aqualung Legend series. A good reg on a par with the Mk25/600 but slightly cheaper. Balanced diaphram 1st and balanced 2nd stages. There are Aqualung dealers in Ireland. Again, not sure where anymore.
Apeks is also a Aqualung brand and is considered one of the best regs for technical divers in cold water enviroments.
Scubapro, Aqualung & Atomic all have a no internet sales clause in their dealer contracts. Be cautious of online sales of these brands. The seller may not be an authorised dealer.
Hope this helps.