Monobloc or concentric

Concentric is cheaper. That's about it. In theory the slide is better supported in the monobloc, so maybe it might last longer. I'd like to replace my twin concentrics with monobloc because they would then look right.

Concentrics take less space  so are more convenient with 2 or 3 carbs. Also less sensitive to sideways forces, so better with a side car. Not your problems I suspect.

Other opinions no doubt exist.

Would not fit a concentric if they were half the price. Cheap nasty and look wrong.

I find the Monobloc easier to work on. Changing the jets (e.g. when optimising the mixture) doesn't involve removing the float chamber first. Also, if you do need to work on the float chamber (e.g. change the float needle to stop flooding) you can assemble everything and then pop on the cover, instead of juggling with the bowl, needle, float, pivot pin in a trough, etc and trying to keep everything in alignment as you feed it back onto the carb, then secure everything with 2 chewed Phillips screws which are difficult to locate.

The Concentric was simpler to manufacture and works better on steep downdraft engines, but is a cheap and nasty device in other respects and seems to wear quicker. .

Hello Mono bloc are far better  then any  concentic and far easier to tune parts are very go  and you get a better throttel  response  and last longer then any concentric  and now Pre Mono bloc is making a come back   Yours   Anna J