Just an update to this, it turns out the AvPlan "crashes" were iOS shutting the program down whilst in background tracking mode. A couple of phone calls and some emailed datalogs and the issue is apparently set to be resolved with an update in the next week or so.
For me at least, having a tech-support phone number and someone to talk to has made a big difference to my experience and seems to have been beneficial to both parties. Other than that, the two EFBs are pretty hard to separate. AvPlan does have the Country Airstrip Guide, though, which is useful.