No, there's a growing literature of ways to test using the CMB spectrum. Early universe cosmology (EUC) seems like the most promising arena for testing, and there has been a lot of research activity, publication recently.
Here's a search that digs up some of the papers from 2008 to 2011 that have to do with testable phenomena (so-called phenomenology, research related to testing Lqg). Have a look at some titles, or read the abstracts if you want:
What I quoted was written in 2010. Have to keep abreast.
I keep an eye on half a dozen alternative QG. Been doing so at least as far back as 2005.
If you are urging doing that you are preaching to the converted.
I tend to study and report on what currently has the most activity, is making the most progress in things like modeling EUC, and attracting the most young researchers (PhD students, postdocs) relative to its size. Percentage growth kind of thing.
Right now I see the most progress happening and the most growth in AsymSafe QG and in Loop.
I've noticed an actual LOSS of interest in some of the other QG gambits some of which I used to think were pretty cool. Just how it is. You may operate on entirely different principles