As discussed in Agenda and Notes - 2016-08-03, it seems feasible that a cost-effective infrastructure can be deployed that can provide at least four nines availability and sufficient capacity for InCommon.
The aggregation/signing service
This is not a major concern, assuming a separate distribution layer in the architecture.
Responsiveness / Capacity
Capacity is not sufficiently elastic
As discussed in Agenda and Notes - 2016-08-03, it seems feasible that a cost-effective infrastructure can be deployed that can provide at least four nines availability and sufficient capacity for InCommon.
(We should decide on acceptable response from the distribution service.)
Cost
Cost of elastic capacity not budgeted
UK experience indicates that this should be low, a few hundred dollars per month.
Staff time and attention
Opportunities
Window of opportunity to engage SAML infrastructure components/tools/libraries outside of the usual suspects (Shibboleth, SimpleSAMLphp) to support Federation (large 'F') using MDQ. See this email from Michael Domingues (Iowa) with a fuller explanation.