I have a Viking walking foot with the guidebar. I have a limited liking for them. My issue is that they do not "lock " into place. I find that just moving the quilt sometimes from under the foot will move the bar. This can be frustrating when I want accuarcy. Its just my opinion but the quilting bar is not all that it is cracked up to be.
The blue painters tape allows me to have the desired spacing, plus I can be more creative with angles in the grid. another plus for painters tape is I can see the quilting pattern ahead of time, and make adjustments.
On the other hand Viking does have a walking foot that has actual feet that change out , so you can have a Walking foot with stitch in the ditch foot. That is worth the $$$.