PRO combi are rebadged Vokera boilers, personally I wouldnt have one but they are much better than the Ferrolli, sound like whoever is giving you advice is getting their boilers from Mr centralheating.com as they are pushing both of these boilers just now, if you plan on staying in the property invest an extra couple of hundred quid and get a Worcester, Vaillant and Alpha are my favourites but that is purely through choice , there are many good manufacturers out there but Worcester are giving a 5 year warranty on the CDi models just now and they are a good piece of kit, if you buy crap you will buy twice, I think some of the Glow worm HE boilers are in the same price range as the PRO combi but sorry I dont really have much experience of them hope this helps cheers Ian