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2-I don't think the unit needs the extended range at all. If the unit wasn't weak early on, i would make it 15 range and have it extend the range to 18 as you say. But as how the unit is ATM, it just needs the vet 2 extended range removed only.
3-The only argument to keep the status quo is if the unit was purposely designed to have this feature as one key element of the unit.
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Not really, the unit is designed to have superior performance with veterancy and even now it hardly more cost efficient than other units of its class like penals. One should not simply remove its vet bonus. If its problematic it should simply replaced by something else.