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Right tool for the job. Get the machine for the kind of riding you want to do. Don't bother perverting the wrong one to the task.
The TTR or CRF150 seem like fine choices to me. I suspect the shortcomings would be obvious; basic suspension unworthy of real upgrades and lack of power for climbs. Fine at the start when paddling hills and rolling bumps. Notsomuch as you gain experience and try to wick it up. Notice that Josh's TTR has suspension upgrades many of us would never have even thought of applying. His offering is-IMO-unique in that respect.