The problemas is when this range is making runes into shoebox, that otherwise, would been an ok Rune.
In that case attacking would be their primary function. In such a case I would think 3-5 or 4-5 would be best.
Shadestriker is 3-4 Because it has a big damage output, stealths in its own DMZ, along with its copies. It's VERY hard finding it, and I say this because I've played with it and won games because of it, even with that range.