Gunpowder - Nanban barbarian weapons

There was a thread discussing the merits of Nanban trade & christianity, I'd like to ask a more specific question around gunpowder units.

I've not used any gunpowder weapons yet, having played so far only as shinto factions -destroying any Nanban/Christian buildings I captured and converting the populace back to the old ways.

Looking at the tech tree, I'm pretty sure non-Christian factions can use gunpowder weapons (Teppo) in late development. Has anyone used these weapons -Christian or not?

How useful are they? How do teppo units compare with archers?

Everyone eventually gets gunpowder units, benefits of being Christian is that you get them like 100 turns earlier.
I've used them as Shinto (kept nanban trade ports but matched the Christian conversion with monks and buildings) and to me they seem more defensive than archers, since their range is so much shorter, in the time it would take from them to run up to firing range against archers and shoot a volley, enemy archers (especially bow samurai or other fast reloaders) will have already put you to a point of routing. But a one good volley from several units can hurt ashigaru morale greatly, making defensive battles much easier.
An interesting strategy I tried in castle defense was putting archers on walls and ashigaru spearmen + imported teppo ashigaru down below: it worked like a charm against a much larger force, only drawback being that you need time to set the formation up, or take a guess where the enemy is coming.

Interesting, thanks.

If teppo units have a shorter range than archers, I guess they'd work well when ambushing on a normal battle -i.e. hidden in woods emerging only when the enemy is close enough.

You'd then have to use your (historicaly accurate) trick of mixing teppos with yari/melee units to hold off the inevitable charge (I usually find that the AI charges as soon as its main melee troops come under fire...).

I've used teppo ashiguru from ambush to cause a chain rout of enemy spear ashiguru. Exposing enemy katana and bow units to flank attacks with my yari cav.

Got a Nanban Trade Port but made sure I had a good temple and monks in place to ensure Christianity did not get out of hand. I also did restrict the Europeans when there was 'an incident'...
Early on the 'imported' arquebus troops are simply too expensive and take too long to train for you to have many but they do have their place.

Later on I captured a Nanban Trade Quarter which allowed as many Nanban Trade ships with cannon as I could afford - unlike the cannon bune which is limited to about 3 (from memory) - and they can kick serious bottom!
Had to keep the province and its neighbours well supplied with monks and temples to maintain Buddhism at a reasonable levels but it was worth it for the heavy ships. Two in each trade fleet keeps the pirates away.

Cheers,
Dreadnought1

If you actually develop your monasteries far enough, they start converting neighboring provinces also. If correctly placed, you should be able to cancel out Nanban Quarter conversion with just 2 of these monasteries.
edit: You'd probably still need a monk in the province with the actual Nanban Quarter...

Teppo units are pretty good, but I only in limited numbers. I suspect the kill rate is slower than with bows, but morale effects are valuable.
Also, on castle defense they seem to work really well, as you can put them on the wall and have some archers behind them. Enemy morale seems pretty fickle when assaulting castles, so the Teppo will help to get an early rout. Also, the range is not really a big issue when firing from the castle.

Does anyone know if the matchlocks are more efficient vs. armor than bows, or is it just an expectation I have from earlier TW games?

The only thing that bugs me about the Teppo is that you can't really boost their accuracy with anything but one of the encampment upgrades (and that is only 5%). That means their accuracy will be really poor compared to my bow samurai with the maxed out paper mill and bushido bonus. Even my ashigaru archers have high accuracy with those added on.