Thanks @z.yodler and @tokidoki,
For the record, I made a video recording of my experience with importing my test seed in ZecWallet and ZWallet.
There are chapter marks to facilitate navigation. In short, sync % shows goes up but then resets several times. At ~1h, it disappears for good and the wallet balance doesn’t change anymore.
I am taking this as the end of synchronization since the word “Syncing %” does not show anymore.
However, when I go to the send page “Spendable Balance” is at 0 and stays at 0 until the ~2h mark.
The page also displays “Some funds still confirming”.
Based on this experience and what I read about Blazesync, I can only conclude what I said earlier.
I appreciate the work that @adityapk00 has done on ZecWallet and I have learned a lot from reading his code but when someone compares synchronization times between wallets I think it is only fair to point out that when "sync % disappears, ZecWallet balance is not yet spendable. (or at least not always)
With ZWallet, ZWallet sync test - YouTube
The behavior is pretty much constant. In the best conditions (top of line phone and local deployment of lightwalletd), it can sync in less than 1 mn but the more realistic result is ~3 mn. The “size” of the wallet doesn’t matter too much (1 or 1000 of notes, empty or 1000 of tx). @tokidoki, this is what I meant by there is no trade-off.
@tokidoki I made a video about lightwallet synching. It was made prior to this but is still relevant IMO.