the UP is for profound hearing losses and no there wouldn't be a difference in what he'd be able to hear with the naida UP vs the naida SP the UP just has a wider fitting range for those with profound losses up to 120 dB SP's only go to 110. I think you should definitely ask to try the naidas with tyler it's worth a shot 
because with the sound recover they can take some of his better freqs and put the sounds in the freqs he cant hear as well in and put them in the frequency that he can hear better in if that makes sense
For ex. I can't hear high freqs all that well between 6k and 8k so my audi puts those high frequency sounds onto the mid frequencies so that I can hear them...so liek high pitched door bells sound different now since they are in a different frequency
