Yes I do think you should send me your new 400mm f5.6 for lens testing. I'm totally free (I'll even pay for postage and shipping) and I can garantee that the lens won't come back to you softer (as has been known to happen when you send lenses to canon).
Turnaround times can be a little slow, but I assure you this is only whilst we put the lens through its paces - and for your good self I can even garantee that the lens will get actual infield testing in your main areas of interest.