I bought a set of unmarked acrylic templates years ago and then never used them. It was so long ago, I'm not really sure, but I think I found them tricky to use. I did not trace around them; they are meant to be held in place with one hand while you rotary cut with the other hand. I am not terribly clumsy, but I was not happy with ease of use. The templates had a tendency to slip, which was annoying. This is more of a problem with an acrylic template than with an acrylic ruler for a couple of reasons. One, the template is smaller which makes it more stressful to hold in place than, say, the usual 6" wide quilting ruler. Two, with a template you need to rotary cut around all sides. If you don't have a revolving rotary cutting mat, it is very easy for the template to slip out of place in relation to the fabric (especially if you are cutting layers of fabric) when you try to move the template/fabric layers to get a reasonable cutting angle. If you don't have a revolving cutting mat and also don't move the template/fabric combo around to get a good cutting angle, but instead try to cut around all sides with the rotary cutter, you are very likely to get a less than accurate cut on at least one side. This also makes it trickier to keep control of the rotary cutter blade so you don't accidentally slice yourself. If cutting completely around a shape without a revolving cutting mat, you will at some point be cutting towards yourself (and underneath the arm of the hand that is holding down the template).
Another disadvantage of the unmarked acrylic template set I had was that each template was useful for one, and only one, size of a specific shape. If you want to mix and match shapes, this is harder to do with unmarked templates because you can't be sure which cut size of one shape will match which cut size of another shape.
A set of acrylic templates can work for a specific quilt block -- for example, double wedding ring -- but is much less useful if you are thinking of mixing and matching shapes for multiple blocks.
What I would recommend instead (if you are not in the market for a die cutting machine such as the Accuquilt Go), is to consider buying specialized rulers. With these you can typically cut fabric into strips first, then use the ruler to cut repetitive shapes from the strips. One example of this, for right triangles, is the EZ Angle ruler:
http://www.amazon.com/Quilting-Angle...dp/B005KC3L4U/
With this ruler you can easily cut multiple right triangles out of a layer of fabric strips, and you can cut different sizes of triangles using the same ruler. With this ruler, you don't have the frustration of trying to cut around all 3 sides of a triangle template. Two of the sides have already been formed by the sides of the fabric strips, so you are using the specialized ruler to cut only the third side.
In my opinion, the clear acrylic templates in the Bayside link you provided are outdated. If I did want to purchase a set of templates for rotary cutting, I would prefer Ardco metal templates (window versions, with gripper material on the underneath side so fabric doesn't slip). I actually have used an Ardco hexagon template to cut hexagons for hand piecing. In that particular case, I cut fabric strips to match the width of the hexagon template, which automatically provided 2 of the 6 sides of the hexagon, then placed the Ardco template on 4 to 6 layers of fabric strips to cut the other sides. You could do this with an acrylic template too, but would need to add some kind of non-slip surface to the underside.
