I have similar view points as those mentioned. If a provider has a fan site I will often join to confirm her looks, body and equipment. You may kind of discover their personality, how they may perform, general do's and don't with them. Also, it may help determine if they're more vanilla or kinkier and what they may be open to or not. All of that often helps me decide to see them or not.
Having said that, I think the opportunity the fan sites offer is a complete win win for those in the adult industry, possibly even more so for trans at this time. Since trans porn is already a huge part of it, a good fan site(s) with the ability to potentially meet the performer, is a huge draw. Finding your niche and how to maximize it I believe is what to focus on at first. The girl next door type, the nice but very kinky librarian type girl, the BDSM type girl etc.
You mentioned some customers no longer see you since your fan page work. I don't think many corporations put as much emphasis on current and former customers as new customers, not like they disregard current and old customers but attracting new business is the majority of the focus. While OnlyFans may have the best internal marketing and pay decent, you're still only within OnlyFans. Putting teaser clips on something like PornHub can help you get seen by a multitude of more new customers.
I know several girls making 200K with their fan site and keep a smaller clientele of regulars and are able to be much more selective with new ones. Some are making a lot more but it is work to create new content, imagine it, set it up, record it, edit it, find people to collaborate with and so on, it's not easy money but I think it greatly opens up income streams. Whatever you decide I wish you the absolute best!