Tough decisions you're trying to make. Hopefully hearing some thoughts from others will help. However, once you feel like you've gathered some good information to make a decision for yourself, be sure to confirm your understanding with your derm.
I have lamellar. I'm not naturally very red, but have lots of scaling.
My skin is definitely better now than when I firt started taking Accutane. I started when I was 13, and took Accutane for 14 years. However, I've heard a lot of anecdotal information about some people's ichthyosis spontaneously getting better with age. So I wonder how much of the improvement is due to Accutane, how much due to some spontaneous improvement with aging, and how much due to a better treatment program (it's all trial-and-error, and I'm constantly refining it. It's come a long way since I was 13!).
As I got older, I found that I could decrease my daily dosage of Accutane and get the same results. While I was always challenging what was the lowest dose I could take and still get satisfactory results, my derm really stressed the importance of "drug holidays," where I would stop taking Accutane altogether. He felt (and I think some others agree) that in terms of mitigating the risks (side effects) of Accutane, occasional drug holidays were even more important than continuing the drug but at a lower dose.
I got to a point where I would do 6 months on, 6 months off (of course, I usually picked the summer as the "on" months).
Have you tried any drug holidays yet? What does your derm think about this? Maybe you could try going off Accutane for a few months, and if your skin really gets worse, then go back on. That's basically how I stopped taking Accutane. It wasn't my plan--I didn't set out with a mindset that "I need to stop Accutane." I just started my usual 6 month drug holiday, and when the 6 months were up, Chris and I talked about it, and decided to wait. My skin was in pretty good shape (I wasn't *dying* to go back on Accutane like I sometimes was) and we decided that we'd just play it by ear--whenever my skin got really bad, and I needed a break, that I'd go back on Accutane. That was back in 1998, and I haven't felt like I've needed Accutane since (I know that's at least partly due to the invention and availability of PDS and Dermal Therapy).
I imagine you're probably in a similar place as I am: I'm getting older, I'm getting more risk averse. The thought of any bone changes from Accutane really bother me. I have copies of all my films, taken at least every 2 years, since age 13, and I have no discernible signs of any bone changes. However, as I got older, I definitely felt differently when I was on Accutane. If I was bending over (like to work on a horse's feet), I would have trouble (pain) straightening back up when I was on Accutane. I couldn't sit for long periods of time spectating (especially in bleechers at a sporting event, but even in theater seats) without having discomfort in my knees and my back. This was all very scary to me, and clear evidence that Accutane was doing *something* to my joints. However, all these symptoms would totally disappear shortly after going off Accutane. That's one of the reasons that the scales have tipped toward staying off for me--I can keep my skin looking and feeling "good enough" without it, and I'm more paranoid about bone changes. But if I couldn't adequately control my skin without Accutane, I'd probably still be on it today.
Hope that helps. Let me know if you have any questions about anything I've experienced.