Many years ago I switched to the Legere synthetic reeds and played them for about two years until I went back to well-adjusted cane reeds. The synthetic reed wasn't bad, it just wasn't that good, and I wasn't willing to put up with some of the sound degradation and articulation and response insufficiencies. I kept it in my case for emergencies.
About six months ago I bought one of their newer European cut reeds to have as a backup. That reed was a significant improvement over the earlier model I'd played, but still not anywhere as good as my cane reeds.
In December, after looking at some reviews of Legere's new French cut reed, despite my hesitancy to rely on reviews, I bought one out of curiosity.
I was amazed at how good they are.
With some very small exceptions, the Legere performed as well as a good cane reed, and I've been happy to live with those small exceptions (which I'll mention later). I've switched to these reeds probably permanently.
Why did I switch when one of the Legere's costs about the same as a box of my usual premium reeds?
I don't have to work on reeds anymore! (I hate working on reeds!)
I don't have to fuss with breaking in cane reeds anymore.
I don't have to deal with temperature and humidity changes that can turn a good cane reed into crap.
The Legere's purportedly "last forever" (I expect some degradation eventually, but as much as I don't play anymore, I expect a year or more out of each).
Even with well-adjusted cane reeds, each cane reed in my reed case plays differently than the others, which is not true with the new Legeres.
I expect to be able to play on two Legere reeds at least for a year at about $70 for two instead of buying four or more boxes of premium reeds at twice the price.
What I'm not entirely happy with:
The Legeres are translucent rather than opaque, which makes positioning on the mouthpiece a bit more difficult.
Precise reed placement on the mouthpiece is critical, especially at the tip. Small changes make a big difference compared to cane.
At least on my mouthpiece, intonation suffers on notes higher than high G above the staff, which certainly doesn't come up very much in most pieces.
The slower register is SLIGHTLY less resonant than with my cane reeds, but not enough for most people and most players to notice.
At the price, you gotta be careful you don't bung up the tip of the reed.
Why I think you should consider buying one:
Most players who are not experts at adjusting reeds will have a reed that is as good or better than the best cane reed they can find out of a box.
Most players, I'm guessing, may be able to play one "forever" without seeing any degradation.
Beginning and intermediate players will be able to experience how a really good reed plays. (I always have recommended them for beginning students past the point where they ding up reeds or otherwise abuse them.)
Buying one:
The reed strength for the Legere French cut model corresponds pretty well with the strengths of Vandoren, D'Addario, and Gonzalez premium reeds.
If your new reed is softer or harder than you want, you can send it back to Legere for exchange as many times as you need to, no charge. (Also see the following note on softening the reeds yourself.)
Some further notes:
The reeds tend to move around on the mouthpiece unless you tighten the ligature more than you may be used to. Though ligature tightness can affect the playing qualities of a cane reed, I don't notice this with the synthetic.
Some people say that fabric ligatures hold the reed better, while others say metal ligatures do better. You choose, but the "hybrid" ligatures I use (fabric with metal rails) work just fine for me.
If your new reed is a bit harder than you'd prefer, you can put it in boiling water for about ten seconds, and that will bring it down about 1/3 strength. (I understand that this can be done multiple times, though I haven't tried it.)
I've tried other synthetics over the years, including the $70+ Alta models. No comparison.
I hope this is useful.
Cheers.