The ability to have individual ringtones (and some other individualized settings) for each user still exists. Each contact must be set up individually in Chomp and it isn't obvious (and yes, I think it's changed in the short time I've been using Chomp). Here is how you currently set up individualized ringtones in Chomp (you will notice other options too):
1. If you do not yet have a conversation thread with the contact of interest, text them so you do.
2. From the Conversations screen, long press on the contact of choice and press "Notifications".
3. Press "Ringtone".
4. Now you see the options that are available. Choose either "Ringtones" or "Music" for a list of the tones on your phone.
5. Select the ringtone you want. You will have to know what the ringtone sounds like based on the file name (since there does not appear to be a way to hear a sample of the sound within Chomp).