I love the performance of the 240 Wby for medium big game but I really am not a fan of the brass, especially Wby brass. Personally, I much favor the 6mm-06 as it will easily match the great performance of the 240 Wby, do so with no fireforming needed and do so with much better, much cheaper, much easier to get brass.
Some will say dies are way to expensive for the 6mm-06, not really. Get a 25-06 FL die, and a 243 FL sizing die, both can be had for around $25-$30 and then just get a 243 bullet seating die and your good to do. Use the 25-06 FL die for body sizing and shoulder bumping if needed, 243 FL die for neck sizing and 243 Seater die to set bullets. Works great. Just have to have the dies set up at the proper height in the press.
Other then brass, I have no issues with the 240 at all, great performance as mentioned. You would be better served as mentioned with a bit faster twist. I use alot of Lilja barrels and have found that in Lilja barrels, a 1-8 is a bit fast for most long range, thin jacketes match bullets such as the A-Max and Berger. With the velocity of the 240 which falls right in there with the 6-284 and 6-06, the 1-9 twist barrels are plenty for anything up to 107 gr SMK plus they tend to allow a bit more velocity potential before bullets start to come apart at these high speeds possible with these chamberings. Again, this is generally with Lilja barrels, other 1-8 twists may be fine, I just find there is no need for this much twist in this class of 6mm for 105 to 107 grain bullets.
I put together a 240 Wby together this summer for a customer in an 8 lb rifle and tested it at 900 yards using the 95 gr Ballistic tip as it had a 1-10 twist barrel. Normally I would never test a rifle this light at 900 yards but I was testing a couple other rifles and was already set up so I decided what the heck. The little, light 240 Wby met my accuracy requirements at 900 yards easily, I was very impressed with its performance. Now conditions were very good but in the right conditions, this level of performance can be very impressive.