I use the shorter adjustable Doo riser. I like it just fine. Main reason to buy it was to get the sled on the deck into the garage. It was a bonus for the maneuverability of the G4. Arms are a little lower and they are stronger that way. IMHO
you want you arms to be slightly bent while your in the attack position ( knees bent etc) , you will see most of the high caliber riders are running quite short risers. This is because the further forward you are on the machine the more control you have. obviously everyone is different, and their riser height requirements are different but the and result we are looking for is the same. Just dont go to short or you will be hunched over all the time and you will be staring and the ground in front of you.
If you are a racer, the attack position is where you should be the most comfy.
If you are a backcountry rider, the sidehill position and the crappy off camber situation position is where you should be most comfy.
Go to the garage, get into the sidehill position, make braaaap braaap noises and notice where your elbows are.
You comfy?
I'm 6'3" and have gone to a flat bar and run the doo adj riser as low as it goes and found I have more control there. Jack the bars back up so you aren't so hunched over killing your back on the trail.