I can see your audiogram now. It’s not that bad. I can see why it’s not bad enough to warrant the use of Speech Rescue. There should be enough amplification to your high frequency area to compensate for the loss. That’s probably why your audi didn’t propose it.
But it doesn’t hurt to explore Speech Rescue and put it in one of the 4 programs you have just to see if you like it enough. You have plenty of Speech Rescue configuration options to choose from based on your loss. I would recommend the 2.4 configuration first, since that’s where your loss is still minimal. And if you don’t like it, switch to the 4.0 configuration next, where the frequency lowering destination region is not as low as the 2.4 configuration, so things may sound a little more natural for you.
As to how the frequency lowering sounds to the ear, I have my Speech Rescue set in the 2.4 configuration and it sounds fine to me. But different people have different perspectives, so your mileage may vary. For me, with Speech Rescue enabled, I can hear a lot more fricatives than before.
Since you mention originally that you’re OK with the OPN 1, but you want to hear fricatives bettter in noisy situations, I would really recommend trying out Speech Rescue. Since your hearing loss is not that severe, you most likely don’t have a feedback issue. So trying out the Speech Rescue option on your existing OPN 1 is a better (and cheaper) approach than laying out an extra $3K on the OPN S1, which doesn’t buy you much more because you don’t have a feedback problem in the first place.
Also make sure you have your audi set the Noise Reduction value in the OpenSound Navigator to the highest value settings, for both Simple and Complex environments. I’ve found that the default Noise Reduction settings, even for the OPN 1, is not the max value, which is not optimal, because why have them in lower settings when the OPN 1 has the ability to give you higher noise reduction values? It’s like having the OPN 1 but only setting the noise reduction capacity to the limits of the OPN 2 or even worse, OPN 3. If that’s the case, you might as well save money and buy the OPN 3 or OPN 2 instead.
If you’re struggling to get speech clarity in noisy situations, the first thing your audi should check is to max out on the noise reduction setting for your OPN 1. Maybe it’s already at max values, but if not, set it to max. Then add Speech Rescue to one of the 4 programs so you can do A/B comparison between the Default program (with no Speech Rescue) and the program that has Speech Rescue and enable, to see if you can get more fricatives out of the Speech Rescue program like you want or not.
Below is an example screen shot of my Speech Rescue page. In your case, I would recommend leaving the High Frequency Bands option to ON, so you can hear both the lowered sound, and the amplified normal sound in the high frequency region. That may help make Speech Rescue sound closer to normal to you because you can hear both the normal and the lowered sound at the same time.
Below is the chart showing how Speech Rescue maps the Source frequency range into the Destination Frequency Range. Also, they’re different than the other frequency lowering technologies which compress the higher frequencies into lower frequencies. Speech Rescue actually does composition (chopping the source range into 3 sections) and transposition (lowering by moving, not by compressing, the chopped sections into the destination range where they’re stacked on top of one another). So I would contend that it may help reduce the distortion from compression because it’s mostly composition and transposition as opposed to compression.