I can't think of any downside, no. And that rule does not prevent you from picking one right now, whether or not you become a club station trustee in the future.
Myself, I have had three different callsigns. My first two were the great in Morse but this last one is horrible in it. But it works fine for voice.
But I never thought about wanting to change what they gave me, any more than I would change the name my mama gave me. The Funny Candy Company gives, and I took. Kinda like the Army.
So if you do decide to pick a callsign, do your research, and as you are looking, think about what it will "mean" - Like this: My second callsign xxxIWL ended in "I Want Love" and my current callsign xxxEM ends in "Easy Money" when I was younger, and "ElMer" now. Whatever you pick, be prepared to live with it for a while.
That rule you cited deals specifically with amateur radio club station trustees, as you pointed out. But that rule is after-the-fact. Right now you are before-the-fact as you pick your first vanity call. Then later, while your vanity callsign is being used by a club, you could not then try to get another vanity call for yourself. You could withdraw as the club's station trustee and force the club to use someone else's callsign, of course, but you can't have two callsigns at the same time.
You will not be restricted in any other way.
So let me tell you a story about how I used my callsign in a couple of very public ways. And why I am so glad it works so well in voice and visually in digital and on my car. You might find an idea or two in this:
First of all are the vanity plates for your car. Most states will give them to you for free. Amateur Radio is a public service. And by free, I mean that in Alaska they are totally free. Not even the normal license plate fees.
I had vanity plates my whole driving life.
Second, I also worked with the Alaska Division of Emergency Services, and the National Guard building packet BBS ID'd itself with my callsign for about a decade.
Packet radio rules are a lot like repeaters. You don't always have to be there; you are required to have positive control at all times, and the operation can be automatic. Also, I had to append a "-1" to my callsign for the PBBS; the ADES packet BBS was xxxEM-1 so I would be allowed to check into it from home or my car using my own callsign.
We actively sought out local hams when there were disasters, like the 37,000 acre Big Lake wildfire.
The FCC established amateur radio as a voluntary, non-commercial, radio communications service. It allows licensed operators to improve their communications and technical skills, while providing the nation with a pool of trained radio operators and technicians who can provide essential communications during emergencies.
Alaska has embraced that concept. The Packet BBS was a great way to get messages out to large numbers of civilians, and to organize volunteers. Since it was operated from the SEOCC at Ft. Richardson, adjacent to the AST dispatch center, it became a great way to send out sitreps and collect information for use in decision-making by the Incident Commanders.
Back to the vanity license plates, the responders in the field are always glad to be able to quickly look at a car and see that it is a ham and not just anyone. They have come to rely on our help. As you get closer then they can look at your window sticker, if you have rank, to determine whether or not to salute. But by then they are at ease because hams are pretty much a known quantity. People who violate the rules do not last in this hobby.
Once you get your preferred callsign, my advice is to get those plates. You have the ticket. So now you have the right to display it for all to see.
No matter what you choose to do let me say Welcome to the community. I trust you will enjoy being a ham for years to come.