In the t/o you describe a nose heavy condition. Because of this the tail has to exert more downward force to counteract the condition which has a net effect of decreasing the performance. On the 340 we can use this to our advantage if the a/c is tail heavy. We get a net increase in performance if cg is greater than 29.
As to this affecting the landing performance you can bet your bottom dollar it has been considered and if it made enough of a difference it would be published in the landing performance data.
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