Yes, I do still practice the Chil Sungs I did learn, even though they aren't taught in my new school. Ill Ro has always been my favorite form to do, mostly because I have a lot of stress in my life, and the extensive breathing in it helps me with that. Ee Ro I practice on rare occasions, but I still do it.
I no longer practice the chil sung forms. I have three tai chi forms that I practice in order to get the benefits of slow breathing and chi work.
The Chil Sung forms I learned were always my favorite of all the forms I learned (with the possible exception of Pyung Ahn O Dan) and I believe they should be taught.
The chil sung forms are cool forms, when practiced correctly. In my conception of TSD, however, they didn't fit. We had been practicing them how I was taught, but how I was taught was wrong because many changes had been made. Dropping them was a move to preserve the integrity of my art. I no longer even practice them, preferring to focus on the Okinawan and Japanese forms.
However, I would encourage you to keep practicing the chil sung forms and forming your own ideas regarding them. Keep sharing and you'll teach me a thing or two.