How is the 4900ex?

Been thinking About trucks I could possibly buy in the future to occupy my mind. Looking at ordering a 4900ex with either a DD13 or 15 and a 10 speed.

Any of you guys have a 4900ex? If so how do you like them?

 

I've been driving a 13 speed here for a little bit and have had nothing but issues. Might be because the truck is used, but has been nothing but a pain.

 

Might be me and not the trans, but it'll kick into neutral when I split certain top gears.

Like I said, could just be user issue, but a good example is I'm climbing up a hill and have to go to low 10, then I go down hill and try to switch to 10 high, it won't go. It's just rolls down the hill in neutral. I'll floor it and the RPMs stay steadily at 14. If I try to switch to 10 high while this is going on and I step on the fuel to engage it into gear, it'll rev up to the 20s while grinding like hell before knocking strongly back into gear.

Another issue is when I'm switching from 5 low to 4. Sometimes it doesn't lock into gear even tho it's in the hole. It'll do the same thing, I give it fuel, grinding revs in the 20s then knocking into gear.

Again, could just be user error! If so I'd like to know how to fix it