HI we are currently following the similar method as you. The students practice on the task trainers for BP then on each other using only manual methods. We try not to introduce the electronic devices until the students are in term 2 - however they are present in all clinical settings. Faculty then use a teaching stethoscope to evaluate the accuracy of the BP and HR with the student. Since we can set the BP on the task trainers, we can tell the students how far off they are when they are practicing. It is a long process and it continues outside the lab in the clinical setting as well.
I look forward to hearing what other people are doing