First point: I have a Boilermate 2000 and am not a plumber or gas engineer but I have heard a lot from people who are.
Second point: A lot of plumbers who don't understand the Boilermate will tell you it's rubbish and to bin yours. Fair enough. However, what you need to remember is that your hot water and heating systems run off the Boilermate with pipework that was probably installed during the house build.
If you decide to replace your Boilermate with a new boiler and cylinder you may need all new pipework. Unfortunately, if your pipework is hidden in the walls or under floorboards, it will cost a fair bit to get any new pipework hidden away. Think lifting carpets and floorboards and with the walls, removing/replacing plaster board then skimming it and then redecorating. The more cost effective alternative? Unsightly surface mounted pipework. Nice!
Next point: Boilermates are fitted with pumps and are/were installed on the first floor of 3 storey townhouses to give the required amount of pressure to bathrooms/ensuites on the top floor. I have been advised by heating engineers that on no account should I consider replacing my Boilermate with a combi boiler as a combi will just not be man enough to get decent hot water pressure on the top floor of my 3 storey house. WRT hot water pressure however, a 2 storey house will probably be a different proposition.
Final point: The cylinders of the Boilermates of the early 2000's (e.g. Boilermate 2000) will not last forever - I have been advised maybe 20 to 25 years. Unfortunately, you can't see the cylinder so won't know what condition it is in. You have to wait for it to fail (leak) to know it has failed. The early PCB's were also prone to failure but that apparently has been fixed now.
The biggest deal-breaker I can see right now is that sourcing new pumps for the Boilermate 2000 is becoming increasingly difficult. This is because although replacements are still manufactured in Europe, those pumps needed for the Boilermate 2000 cannot be imported as they don't meet the Goverments efficiency standards.
So, the bottom line? Whether you replace your Boilermate 2000 with the latest version or opt for a system boiler and cylinder, getting enough hot water pressure on the top floor of a 3 storey house is not going to be cheap exercise.
