Been using pg-promise[1] for years (for Node). How does this compare - is there a reason to switch? [1]: https://github.com/vitaly-t/pg-promise
If you check out the documentation I think you should be able to see if it's worth it for you to switch. My personal top reason is the safe query writing using tagged template literals, and the simpler more concise general usage. Then there's a lot around connection handling which is simpler, but also handles more cases. Then there's the performance. Postgres.js implicitly creates prepared statements which not only makes everything faster, but it also lowers the amount of work your database has to do. Pipelining also happens by default. As you can see by the benchmarks listed elsewhere, Postgres.js is quite a bit faster, so you can either get more oomph out of your current setup, or scale down to save some money ;)
Even so, if pg-promise works for you as it is, it might not make much sense to switch, but if you have the connection slots for it, you can run them side by side to get a feel for it too.
Another thing I remember when starting with pg-promise was the return value helpers, which I used a lot. Now - I think it's much nicer to have the simple API, and simple return value being an array, like Postgres.js does[1]. Especially now that we have destructuring, it just looks like this:
const [user] = await sql`...`