  We examine the utility of very high redshift Type Ia supernovae for cosmology
and systematic uncertainty control. Next generation space surveys such as the
Supernova/Acceleration Probe (SNAP) will obtain thousands of supernovae at
z>1.7, beyond the design redshift for which the supernovae will be exquisitely
characterized. We find that any z\gtrsim2 standard candles' use for
cosmological parameter estimation is quite modest and subject to pitfalls; we
examine gravitational lensing, redshift calibration, and contamination effects
in some detail. The very high redshift supernovae - both thermonuclear and core
collapse - will provide copious interesting information on star formation,
environment, and evolution. However, the new observational systematics that
must be faced, as well as the limited expansion of SN-parameter space afforded,
does not point to high value for 1.7<z<3 SNe Ia in controlling evolutionary
systematics relative to what SNAP can already achieve at z<1.7. Synergy with
observations from JWST and thirty meter class telescopes afford rich
opportunities for advances throughout astrophysics.
