I feel it is worth the sacrifice. The biggest problem with spear/staff and pole specs is the loss of your dual wield attacks and thus your over all damage output is greatly decreased. A felar spear/staff or pole spec does not have this limitation and still gets the great defense from the weapon. I would not choose polearm though as the str is a greater factor with this spec as there are fewer light polearms.

Even given the slightly better dex and str and I still prefer a felar with a spear/staff the extra con(+4) and the extra attacks will in my opinion more then make up for the -2 str and the -1 dex in your example.

aside note: Felar have a bonus with hand to hand, that is there claws, another little benefit of this combo.