Hello Giuseppe,
To be honest with you, I'm not sure if the designers of the SCXI-1351 were concerned with possible overshoots in the signal. I'm also a little rusty on my filter design, but I believe that a higher order Butterworth filter offers a steeper rate of attenuation at the cost of ringing and phase linearity just as you mentioned. Like most designs, the choice of any filter offers both advantages and disadvantages over other filters. It is really up to you in terms of what you believe your signal will benefit most from (steeper roll-off, less overshoot, phase linearity, etc.) in order to determine which signal conditioner is best for your application. And as you mentioned, it's not always an easy decision.
Take care,
E.Lee
Eric
DE For Life!