AFAIK you can only get travel insurance with VHI if your health insurance is with them, it was always advertised as such so doubt there's any issue with that.
Ours has been with ACE through AIB for the past couple of years. You just missed a 20% off offer that ended yesterday.
Plenty of options out there, depends on where you're going really. As we gotto the US a lot I always ensure that there is at least €2,500,000 medical cover on top of our health insurance. Sounds excessive until you look at what US hospitals charge!