We really liked the flip trainer. They look a little different from the flip system. We used flip diapers beforehand as well. They are pretty darn waterproof and that's what i loved. For nights, i put two inserts in it and it worked fine. My daughter was able to pull them up and down fine.
We tried the Grovia but they looked like booty shorts on my fuller figured toddler. Lol! Her little butt cheeks hung out. We tried those at night once and it leaked horribly. I may have not prepped it enough. I sold those almost immediately.
We also used the Bububibi trainers when she got more independent. They are made out of bamboo, fairly inexpensive, minky outer, and hold a pretty good-sized accident. Those may be worth looking into as well. I think they were $6 each when i bought them.