I've got a question for the "don't use the tick mark" contingent: have you measured any inaccuracy in the placement of the tick marks?
Manufacturing quality of the Suzuki parts I have worked with has been excellent. I've been in manufacturing myself for decades and based on the high degree of accuracy I've seen in Japanese motorcycles, I would be inclined to say the marks are a very good way to get basic alignment. The swingarms are made on automated equipment which intrinsically produces very tight tolerances. The marks are, undoubtedly, placed with the swingarm in a fixture that maintains good alignment and yields repeatable, accurate placement of the tick marks.
Being a stickler for detail, I would be inclined, at least once, to verify the accuracy of these marks just for peace of mind. Once that is done, using the swingarm marks should be just fine.