Yes, Geosphere has access to accessing your location even when you have left the app, so it could be using GPS and battery while you are not actively in the app.
Cachly doesn't do this, and only uses GPS while the app is active.
I'm a longtime Geosphere user as well. I agree it can drain the battery quickly unless the GPS turned off. One big difference between Geosphere and Cahly though appears to be in the device Privacy Settings. Cachly has the "while using app" option under location services. Geosphere has "always".
I've made an almost 100% switch to Cachly. Perhaps with version 2.0 I'll complete that swith complete that switch.