BBS02 noob questions

I have been reading through the BBS02 threads, trying to figure out what best would meet my needs/wants. 350 would probably meet my regular needs (commuting/hauling kids/light cargo) but i have a hankering to occasionally climb some local mountain roads, so 500/750 is really appealing considering it doesn't cost very much more and you can also go faster on the flats if one wants to, vs. a 350w. Most things i read here and there also tell me that hub motors will conk out on any extended climbs so I am heading towards the bafeng.

So, (submitting humbly these questions to the collective)-

What are the biggest pros/cons for choosing a 500W/18A limit on a 750W motor? increased motor longevity?
Would/wouldn't it be just as practical to go with the 750W/25A but stay at lower PAS/throttle programming limits unless you really need the extra power on occasion?
Anyone have an idea of any kind on the lifespan/longevity of the BBS02 with what might be considered normal usage ( commuting, hauling light cargo/passengers, etc, relatively flat city riding )?
Definitely getting some anecdotal evidence here of bbs02 failures, wondering how big the failure rate is, and if this means it makes more sense to go with a local supplier in USA vs ordering from China to save a few hundred bucks? seems like some people have gotten stuck with defective motors/controllers and others have done just fine.
Has anybody here put a bbs02 on an Xtracycle or other cargo bike and what's your feedback so far ?

Many thanks for everyone putting so much knowledge out here in the forums open source style. It's a huge help.

Personally I would go with the 750 as you can always use less power as you said.
If you look through these forums you will find a few people have had problems BUT of course you dont hear about the tens of thousands that DONT have a problem.
Buying locally saves you having any customs problems and of course you always have someone to complain to if you get problems although that just means that they have to deal with their chinese suppliers,you will still have to wait the same length of time for spares(usually).
Mine is fitted to an MTB so the only cargo it has to pull is 108Kg of me but it does it up 20% hills without problems.

What are the biggest pros/cons for choosing a 500W/18A limit on a 750W motor? increased motor longevity?

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Thats what i did. Bought the 500W ( a de-rated 750W) so that i would get the 9 Fet rather than 6 Fet controller. Thinking is that the 9 Fet is more robust and less likely to pop something.

Also, limiting it to 18A matched the discharge capacity of the battery i bought. 48V/11 aH, Samsung 29E cells.

Discharge Current, recommended 20A continuous (BMS Limited, see following suggestions regardfing specific cell types). There is very limited space in the case for a larger BMS, plus the BMS must include the remote power on/off function, which further restricts the choice of suitable BMS. We recommend a controller rating of approx ~17A with the 22P pack, ~22A with the 29E pack. The high Power 20R pack can deliver 30A or more, but we recomemnd the continuous discharge rate is kept within reasonable limits to avoid stressing the BMS. This is not a high power battery pack, at least not by EM3ev standards.

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anyone have experience riding all 4 motors ( 36/350, 36/500, 48/500, 48/750) and can speak to the difference in power/feel amongst them?

I also have a BBS02-750W kit. One of the earlier 6FET versions.
So far, I have only had to repair a mangled O-ring at the Journal Bearing, and ultimately regreased the whole inner workings at around 400 miles. I have since ridden another 800+ miles without any major issues. The original 6FET controller programmed to 25A and Unlimited speed has held up quite fine, although I did buy a spare 9FET controller as a back-up.
If you think you might want the extra power, your WILL want it at some point- I guarantee it. Get the 750W and be done with it. You can always reprogram the controller to derate it to 18A Max current and fine tune the PAS settings to suit your riding.