We are replacing an existing Thermador downdraft (the retracting type that goes behind cooktop) with a Bosch model (HDD 80051UC). You have to buy the blower separately, and there are three choices: Flexible, In-line, and Remote. We assume we'll need to go with the Flexible (DHG602 DUC) to best match the existing setup, but we want to be sure, since the blowers are not returnable. Also, we aren't sure whether the duct sizes are the same as our existing ductwork, which exhausts through base of brick wall. We won't know this until after demolition, at which point it might be late to order the blower. Does anyone have experience installing this type of Bosch downdraft and the Flexible blower?