I have the Timberlines, which, by the way, are a phenomenal boot, and am also looking for a 6" boot. All my life, I've used trail runners and locking my ankles up in tall boots like the Timberlines is not comfortable for me.
Over decades, I've contorted my ankles stepping on downed branches, or loose rocks, but never strained or sprained them. As soon as I started locking up my ankles in the Timberlines, I think the energy involved in twisting my foot in an odd manner gets transferred to or absorbed by my knee. They've been hurting lately and I've never had a problem until I wore tall boots. I don't want to have knee problems.
I'll continue to use my Timberlines but will only lace them up part way. Meanwhile, I'm on the hunt for a 6" version of the Timberline. I tried the Schnee Divide Mid but they fit tighter than the Timberline. I am definitely going to try the Schnee Kestrel.
A short answer to your original question about whether a tall boot gets in the way or makes walking more difficult is....Yes and Yes...at least for me. A significant difference and I haven't found any benefit to make up for the downsides of a tall boot. They're not for me.