I've been really happy with the print quality I'm getting on the gloss vinyl. Actually prefer it over IJ35.
If I had one complaint, it would be the liner. That's where the price difference is as compared to Oracal or 3M.
As long as the material is running through the machine, no issue. Let it sit in the printer for more than a few minutes before printing and you'll get buckling. You need to advance until you get material fresh off the roll. Definitely not a material you leave sit in the machine if only printing jobs here and there. My solution has been to print full rolls if possible, or cut the material at the back of the machine when done printing and roll it back up. Saves a couple feet. I know it's pretty economical media, but over the course of a roll, it adds up.
Regardless, I've run about 6 rolls to date. No print issues, no install failures, no noticeable shrink. All in all, a darn good media.
I've used the lam as well. Gloss is real good, matte is nice, but more of a textured matte. If a client has been used to receiving 210 matte, that's what they get. New clients get the Instant Media matte. No complaints so far.