I do recommend watching the Nancys Notions video link (below) to get an idea of how effective quilting with rulers can be.
Nancys Notions Ruler Foot
I have completed "Poppy Lane" sample quilt for my Enhance and Mellow class coming out later this year at Sawmillers Quiltery. I used the Ruler foot and a clamshell ruler from Handi Quilter to quilt this quilt. I definitely needed the help of my supreme slider quilting mat to help the quilt slide freely.
Supreme slider link
The quilting is a little rough in places. My stitches are not even and I found I tended to slip the ruler so some of my clam shells are not event. I did scratch the ruler by placing it on top of my pins so I do recommend taking your pins out. Part of learning as we go and I definitely need more practise.
I have enjoyed testing out the 1/4" ruler foot and will continue to use this method on some of my quilts. In New Zealand the access to rulers is very limited. Stewmac are the NZ distributors for Handiquilter rulers. Quiltique.co.nz also supplies machine quilting rulers (my friend has bought some for her HQ sweet sixteen) however I cannot find the rulers listed on their website. Will update this post when I receive more information.
Now - of to play with my new sewing machine gadget "flower foot"