Indeed, and as Sw1ller has pointed out, if a 150 on one engine can cope with the timings, then a 230 with good acceleration but only 60mph top speed will probably be ok too. Knowing how protective Virgin can be though it wouldn't surprise me if they objected!
My main concern however is the layout of the units. I know we haven't seen exactly what they're going to look like inside, and they are slightly longer then a 150, but I'm still concerned that a metro style layout with so many doors is going to provide too few seats and too little luggage space for this service. The 150s already struggle at times, especially on the luggage issue, and I can't see how these units are going to cope. I know it's only 23 minutes, and it's only for a few years, but it's still going to reflect excellent poorly on the franchise, especially for passengers changing at Crewe.