First of all, congratulations on doing do well with your workouts. I'm not a Firm user myself but I hear they're really tough workouts and you should feel super proud for sticking with it. I'm a big Cathe fan, like pretty much everyone on here, and I just wanted to add that if you like hi/lo cardio and step you might want to get the Maximum Intensity Cardio tape. I love that one. It's either 2 separate shorter cardio workouts or one really long, kickbutt workout. She does a fun, low impact warmup (thorough with plenty of stretching of course) and then does low impact, medium impact and good old fashioned high impact cardio for about 30 minutes. Then if you're not dripping sweat and exhausted already, you can keep going with 30 minutes of fun stepping, which concludes with some tough intervals to that will really have you either feeling like Wonder Woman or wanting to kill Cathe, or both! But I think it's a really fun cardio tape, I break it up and use it separately on weight training days and even that's good enough.
You also might like Bodymax, which is 90 minutes and is another one you can break up or do all the way through. It's a good warmup, high intensity stepping, then alternating circuits of stepping with weight training for legs, then upper body weight lifting and abs. It's really tough, really thorough and tons of fun.
Finally, my other favorite Cathe tape is the Interval Max tape, which I think ties with Circuit Max for my all time favorite of hers. Interval Max is really killer. It uses power bursts of getting breathless and really fatigued with moderate paced cardio back and forth for 10 intervals. Super tough, great for revving the metabolism and a lot of fun because of the athletic moves and easy to follow choreography. Circuit Max is a new fave, giving you hi/lo (2 segments), kickboxing (2 segments) and step (2 segments) alternated with shoulders, bis and tris with weights. She finishes with back, chest and abwork (using some less conventional core stablizing techniques rather than crunches.) Those are both a lot of fun and really tough, too.
So, those are my particular faves that you might really enjoy, too. Hope that helps. I firmly believe Cathe's tapes can push you from intermediate to advanced if you stick with them and just have fun. They did that for me!