recently installed a Stanley Oisin (non boiler) stove. I was looking at the possibility of having a boiler model installed. However, as it transpires I'm just as happy not to have gone that route. First of all, retrofitting it would have been an expensive nightmare. Secondly, with the boiler models, you really need to go for bigger stoves as you won't get as much heat into the room as a result.
I have used the Oisin rarely - and that may remain the case for the short/medium term. However, just sealing off that opening is a major improvement to the energy efficiency of a dwelling - and given that this particular stove was cheap as chips and I self installed, it will pay for itself even if I never use it - by making the house more airtight.
So, make sure you get a stove big enough to both act as a room heater and circulate hot water. As a result, be prepared to have the fuel available to feed a bigger stove.
Also worth noting is that there are a handful of proper room sealed solid fuel stoves on the market now ie. they have their own dedicated air supply. However, if you go this router, be prepared to spend much more and also take care that you get someone competent to install.