Hope Admin picks up on this because I too would like the answer. I range from 20 to 105 and a lot the aids that might be appropriate for my higher frequency loss (Naida, Sumo DM, Xtreme) have ranges that start at 50 or 60.
I suspect Phonak does have expansion and that the fitting range is an indication of optimal audiological suitability (and tends to quote aids that can take both standard moulds and slim tubes on their moulded fitting range) rather than excluding certain losses. For instance I recently fitted a Naida III to a client with a dead ear on one side and a High frequency dead range in his usable ear (20db - 250-500Hz, 30db - 1Khz, 65dB -1,5kHZ, 80- 2Khz and then no response above). After extensive contact with Phonak re suitability (As I really wanted to see how effective Frequency compression (SoundRecover) would be for this client who is not interested in Cochelar implant, but finds little benefit with traditional amplification in his good ear), I proceeded to fit him in his better ear only using a Large (4mm) vent. The device was able to match the target (REM - NL-1) extremely well after turning off BassBoost and setting the occlusion manager to -3. The client found the device very quiet re internal noise (completely silent in the booth) and experienced neither occlusion (due to the large vent) nor ampclusion (due to the extra large receiver). Feedback was also a non-issue. I turned down the MPO somewhat to prevent any noise induced damage. We experimented with various SoundRecover strengths (more or less frequency compression) and he was able to notice an improved clarity almost immediately superior to the several other devices we tried before.
Only time will tell how he adapts and how much additional speech discrimination he obtains as Phonak suggests adaptation could take up to 3 months or more to show a marked difference. Fortunately he is highly motivated and keen to try new hearing aid tech.
It is thus worthwhile trying some of these devices as long as they are flexible enough to be altered to suit your hearing and your professional takes due care to protect your existing hearing. The Phonak reps did mention that Phonak might be bringing out a less powerful device in the future that has SoundRecover specifically designed for severe high frequency losses. We will just have to wait and see.