I think you want people to spend some more coin as even 5yr warranty is good,but 10 yr,That's Bryston all over it.
Have to say two other very well known sub companies which I used their warranty was 1-2 yr and all those subs I had, had amp trouble or they just died.4 of them I bought used(only 1.5 yr. old,new well over 3000)not impressed.
I recall reading an article in Stereophile way back when (at least 10+ years) written by Russ Herschelmann where he recommended using passive subs for a variety of reasons. My first sub was powered but then I replaced them with very well regarded passive subs. I found this very beneficial because:
1. I just needed to run speaker cable to the passive sub vs running a line level cable and power cable if there was no outlet nearby.
2. I could choose my amps. Yes this an expensive proposition. The amps generally found in subs are not exactly high quality as per the quote above.
3. it made running multiple subs easier (some amps have daisy chaining capabilities and or have the one mono signal sent to both channels without the use of a splitter)
4. In addition to the amps, I had to add my own PEQ - again more $ but more flexible
Subs will generally come in these flavours
A. self powered (majority of the market)
B. passive but accompanied by an external power amp
C. passive
Maybe Bryston should consider option B or even C so servicing could be easier and provide more flexibility. If option B, then the woofer and cabinet can also be warranted differently / seperately from the amplifer. If the Bryston sub is servo controlled C is probably not an option. If mating the amp with the sub is critical maybe a combination of A and B. Design the sub so the amp can be integrated as part of the sub eg sits on top of the sub so it is essentially A but the self contained amp section can be placed in a different location essentially B.