Buy it if you can, i have owned a RB44 for 18 months i know everyone has a different view on the Boughton and its Alleged faults etc, having spoken to the Manufacturer and those that used them all have a different view on it's faults and Capabilities. The braking and pulling to left or right under brake load all appear to have been sorted by the in service mods, i can only speak from using the vehicle and have found the following, It goes like stink if you are so Inclined it will go off the speedo it will drive up the side of a house, it stops in a dead Straight line breaking is excellent, fuel economy is great better than some landies i have owned i thought at least 20+mpg but another Boughton owner has worked out that if he keeps below 60mph a steady 50mph returns over 30mpg this i cannot confirm but mine seems brill on fuel, it never fails to start Perkins T4 great engine it has a speed limiter fitted so you cannot thrash the gears but you can pull wheelies in first when pulling away if you like:-D.
As for working on it the whole front including bonnet can be taken off easy access to rad etc. I have in just over an hour had all the front seat's out engine cover and side wall's and cab floor out this means you have all round access to gear box/transfer box and most of the engine.
Parts for the engine are Commercially available and other parts are becoming much easier to find now.
My own personal view is its a great 4x4 much more fun than a landrover and great cross country(i live on the southdowns) Permanent 4 wheel drive diff locks and hi/lo range its a very cheap unimog.
Anyway thats my waffle over i hope this helps.