Well I'm gonna totally go against the majority out here and NOT by experience, let me say again not by "MY OWN EXPERIENCE". I work in whats called the expediting industry (basically delivering freight like 18 wheelers) only, in a van. I discuss, communicate & swap information regarding all types of vans on a daily, weekly, monthly basis with hundreds of members within our own expediting community. We have folks driving the promasters, transits, mercedes, nissans, chevys Etc. Etc. And as I stated we continually discuss the ins and outs of ALL these vans trying to gain a general understanding of which one would or is the more profitable, safest, mechanically sound van to stay or go with.
I told you the back story to give some validity to what im about to tell you, apologies, LOL.
So in the time I been doing this I have crossed paths with quite a few guys who do in fact run the 6 cyl. Chevy vans out here in (the expediting) industry, which means they haul in these 6 cyl Chevy vans on a regular basis anywhere from 100lbs to 2,500lbs REGULARLY in the back of these vans. The load changes frequently, its not a consistent 2,500lbs nor is it a consistent 100lbs so the weight they carry changes from load to load. But do understand, they are traveling (NON-STOP) everyday putting the van through its paces hundreds of thousands of miles weekly! Is it as strong as a V8, no. Is it gonna pull like a V8, no. But the question was asked concerning a V6 so my input is a V6 can and does do the same job as a V8 and does it as long as a V8 so long as the driver keeps up general maintenance.
So YES the V6 Express is plenty strong enough.
The drivers I speak to who run these vans love them, say they do the job thats asked of them, do they complain about a lack of power goin up mountains in Colorado, yes. But overall they have no problems with the vans so long as you know the task that is sat in front of you when hauling a particular amount of weight. We have drivers out here getting in excess of a million miles on some of these gasoline engines and then we have guys that only get 200k and KABOOM! Its all in preventative maintenance and driver ability to asess the obstacle put before the van in question on how hard to push it or rather take it nice and easy. You have drivers hammering down on the gas pedal, engaging the passing gear going up a mountain the entire way up without letting off (thats the 200k or less guy). Then you have the smart guy who babys it the entire way up, or gets a good start on the hill in front of him without engaging the engine hard or pounding the trannys passing gear, the guy hammering down gonna get to the top what, 20 seconds faster? Is that 20 seconds worth losing a tranny or blowing an engine?
By the way, I have a 2017 Ford Transit T350 Eco Boost Brand new off the lot, 9 months old. I have 107,000+ miles on it.