Hi,
now I run my Emco with 125 mm chuck for more than 6 months without problems. As long as one keeps himself under 3000 r / min so everything works as usual. I can run the example M04 S2500 and change without delay to the M03 S2500. Is there reason to drive at higher speeds, you get change chuck.
To turn at 4000 r / min for 50mm axles can hardly be needed even with hard metal plates. The new chuck takes a little more space ~ 15mm but I think the benefits you have the 30mm large center hole gives me more compliments than the naktdelen opportunities that I may run a little shorter pieces.

My last treatment was to turn down the shaft 6mm to 4mm on stock fit.
I probably would not have believed from the beginning that I would be happy with the surface but the 3000 r / min was OK. One feels himself limited by the 3000V can be by increasing to 120% or increase in smaller increments to a maximum lap without any problems.
However, one must decelerate accordingly, otherwise the machine will blow in case of rapid deceleration of the chuck. My steel chuck is good for 5000 r / min as it is generous.
So my answer is that I'm very happy with my current account chuck