Regarding the round trip duration: Minibits can't fully match the latencies of custodial / server side wallets.

When you zap someone with nwc, published event with encrypted command is read by the server but then encrypted again with server key and routed through remote data push message to target device with Minibits wallet. 

After wakeup, Minibits asks mint for a mint quote, might need an ecash swap with the mint to prepare the ecash and forwards it to the mint.

The mint settles an invoice, it is then still upon receiver to figure that out and to publish the receipt.

I would say, one should not expect that to match custodial lightning wallet latency.