All brokers are about the same.
The downside worries are:
1 . Negative balance protection
2. Spreads and Fill
3. Lag and server hang issues
In terms of regulation, no one will worry about FXCM so much compared to other brokers based on shady places.
But FXCM itself, spreads are not that ideal. Reputation is good but they were also hit bye CHF movement last year, and had lost massive money and clients due to that incident.
I would still prefer negative balance protection regardless of broker.
But your amount is significantly higher than most retail FX traders here. You probably know best.