What to compare on your account:
- Average range from 08:00 to 10:00 London on both pairs. EURCHF is typically well under half of EURUSD.
- Average spread. EURCHF spreads are often around 1 pip or more at retail brokers.
- How often each pair makes false breaks of the Asian range.
Cleaner moves, if you find them, don't fix the cost problem.
The main risk is the SNB. Even with no scheduled event, CHF can jump on headlines, so size should stay small.
A reasonable compromise: keep EURCHF on the watchlist for days with Swiss data, not as a daily pair. Does anyone scalp it regularly?