I would say that the SWAM instruments (https://audiomodeling.com/solo-woodwinds/) are incredibly good, and if you want to sound like a flute or sax, you won't regret getting a platform that can run the SWAM plugins.

I bought my Sylphyo before the upgrade was available and invested hours looking for the "perfect" flute sound for my iPhone.

I ended up using BS-16i on my iPhone. It is definitely an excellent lightweight solution. It works out of the box with the Sylphyo, is easy to use and has very low latency. Though the BS-16i came with hundreds of instrument presets built in, I generally use the Ixox flute sound font as this sounds very close to my own flute.

The great thing with the Sylphyo is that there is no limit to the different ways that you can go.

Two additional forums that I found very useful when starting off were patchman and audiobus

You could use any number of apps on an iPad or computer, but you'll need to configure the parameters in most to work well with the various CC messages Sylphyo sends out. The onboard sounds just work.

One thing to consider is this: the more sounds/patches you have to choose from, the more time you'll spend choosing patches instead of playing. I can say this from experience and have personally chosen to simplify and concentrate on enjoying playing.

Peace.