OK, I looked at a specific case for a Pepper user and I think it illustrates the point well
Now that the fixed rates have risen, it looks as if someone on a margin of 1% should probably stay on it. When rates were lower, it did make sense in many cases to switch.
Summary facts
Tracker margin: 1%
Mortgage of €170k on a house worth €460k
No intention to overpay
No barriers to switching
Not a high Ber rating.
With the ECB rate at 2.5 %, you are currently paying 3.5%.
The problem is that we don't know how interest rates will go in the medium to long term. Economists have been very poor at forecasting. The ECB rate is more likely to rise than fall in the short term but you have 15 years left on your mortgage.
You can't fix with Pepper, so you would have to switch to another lender.
You have an LTV of <50%
Fixing for a short term e.g. 5 years, is not a good idea, as you would then lose the tracker for the remaining 10 years.
You could fix with Bank of Ireland for 10 years at 3.55%. You would then be vulnerable to Bank of Ireland's exploitative treatment of existing customers for the remaining 8 years. It wouldn't matter too much as your balance will be lower, but then as your balance will be lower, it won't justify switching from BoI to a cheaper rate. But Bank of Ireland is behind the other lenders in this rate cycle and so by the time you get approval, rates may have risen anyway.
If you look at a fair lender like AIB or Avant, for 7 years fixed they are charging 3.95% and 4.05%. I see no point in going to the hassle and expense of switching to them.
So overall, it's a close call, but you are probably better off sticking with your tracker.
Brendan