You can get the TSDZ2 with a double chainring, but I'm not sure how happy an Alfine would be running one, since Shimano designed to be just a 1x. You'd need to get creative with the chain tensioner. Even if it you could make it work I don't think much would be gained running it as a 16 speed bike since the standard 8 gearing gives a useful spread of gearing.
With my DZ2 running 42:18 gearing (chainring/sprocket) I hardly ever use the lowest 3 or 4 gears and they are only really there as 'get me home gears' for when the battery goes flat, and pedalling a dead 20kg ebike is no fun

. So in effect it's a 4 or 5 speed with motor assistance. The 42/18 tops out at about 25mph, which is enough for ripping round town - I could go faster but I'm not one for peddling like a Tw4t.
I'd like to go a bit higher with the gearing but Aflines like to stick as close to 2:1 ratio as possible (ideally 42:20) and can be prone to damage 'over torquing' if you go outside the recommended ratios. 42:18 works seems to work OK
My battery is known as a 'hailong' (due to the shape of the case), and is a bit smaller than the above mentioned shark. it's 36v 15ah and was from
http://eclipsebikes.com/product_info.php?products_id=107
And I got my motor kit from a reliable firm in China, and it's delivered from their warehouse in Germany, so no silly import taxes
@DaddyPaddey Do you have flats or drop bars?
oh and piccies...
View attachment 463942 View attachment 463943