Broadband in Dunshaughlin

As an existing customer of "Pure Telecom" (for the last three years or so) I rang them today to see if they could offer me a better deal. I am currently paying 50 Euro per month for line rental, local and national calls, and broadband, unlimited, up to 100MB.
My call was prompted by an offer from Pure via One Big Switch, for new customers only...looks very good if you are a first time customer:
25 Euro for first 12 months, then 45 Euro thereafter with an 18 month contract.
So the best they could offer me was a new contract as follows:
45 per month, with 16 Euro discount for the first three months...so much for brand loyalty.
So if I have my maths correct, the three cost scenarios above, over an 18-month period work out as follows:
My current situation: 900 euros
Their new offer to me: 762 euro
New customer: 570

So my question is: should I suck it up and take their new offer, or risk another supplier as a new customer in the hope of getting a similar deal as the Pure new customer?
I'm not well up on the technical side of things but I've had no problems accessing Netflix, YouTube etc on TV, apart from the occasional temporary loss of signal.
If I go with a new supplier would there be a chance of ending up with a worse signal etc?
And would it be worth waiting for Siro before committing to another 18 months with Pure?
Ant thoughts or contributions would be welcome...