As a data point, there are currently 866* x-small IPv4 ISP organizations in the ARIN region.
There are a total of 3,562* ISP organizations in the ARIN region (including IPv4 and IPv6).
x-small IPv4 providers as such, constitute about 1/4 of the total ARIN ISP constituency.
The maximum revenue impact of an IPv6 waiver for them (removing the $1,000 surcharge
for IPv6 /32 pricing) would be $833,000 per year, increasing as the number of organizations
affected by the waiver increased.
This information is provided strictly as a data point and not in the interests of pushing
the discussion in either direction.
*The data I used to produce these numbers comes from ARIN staff and is current as of
earlier April 29, 2010. ARIN will be publishing the data to their statistics page in the next few
days. Please don't blame staff for the publication delay. I asked for the numbers late
last night and they have been extremely responsive in getting the data to me and have
taken the additional initiative to publish it as quickly as they can within their process.