It would be worth finding out what's wrong with the old one, a repair should be way cheaper than a new boiler.
With no disrespect to George, opinions on boilers from plumbers are not dissimilar to opinions on rods or reels from anglers, everyone has a favourite, some will say Worcester,or Vaillant, or Intergas.etc. etc..
Take a couple of photos of the offending area, make sure you have the boiler/system details and get yourself over to UHM for some advice.
http://www.ultimatehandyman.co.uk/forum1/index.php
None taken, like you say we all have our own likes & dislikes, All boilers are pretty much the same Ive just found over the years the one I recommended is very reliable and great aftercare, Ive had no problems with that make or company.
As for fitting & getting them out, never had any problems there either.