I've not had a lot of time to experiment more with the glassless framing of either watercolor or pastel lately but I have been thinking about it a lot. And I've reached a few conclusions about it for me personally and I'll share them with you here.
First, I think glassless framing is very practical. Pastel and watercolor are relatively delicate mediums and the varnish protects them in a way that glass cannot do. However, the very delicacy of the media is what makes them what they are and look as they do. Varnishing changes the look into something else and I'm not so sure that's desirable, especially in every case. If varnishing didn't change the look of the art, I would be wholeheartedly enthusiastic about glassless framing. As it stands, I'm enthusiastic - with some reservations.
In this day and time and especially here in the US, there's a myriad of art media available to artists (and I think I've tried just about all that are out there! lol)
The painting of the cockatoo (varnished watercolor) is hanging on the studio wall where I have to see it on a regular basis. One day as I glanced at it, it struck me that it looks very much like an acrylic ink painting. Varnishing a watercolor is quite a bit of trouble so why bother when the look ends up being very similar to a medium that doesn't require near that amount of effort? Acrylic inks also behave so much like watercolor that if one is mastered, then the other can be also. Perhaps the major difference is that the acrylic inks cannot be re-wet or lifted once they're dry, otherwise, they're very, very similar to work with.
Pastel is another matter altogether. Right now there's really not any other medium that looks or behaves quite like soft pastels or pastel pencils. Even after it's varnished, it has it's own look. Of course, the average person probably wouldn't be able to tell the difference between a varnished pastel, a varnished watercolor or an acrylic ink painting. Once finished, they all look very similar. And, without the texture, an oil or regular acrylic would probably look very close to the other mediums if all were varnished with the same type/finish of varnish.
So, right now, with technology as it is, I don't think I'm going to pursue glassless framing, especially for pastels. As I've said, if I could do it without changing the look of the original medium, I'd do it in a heartbeat. But, since the varnish is an extra process and changes the look of pastel and watercolor into something else entirely, I say why bother?