Kenwood KFCs = Bad??

Hi everyone. I have a non-jbl stock system in my 2017 SR5 (double cab). I purchased the truck in November and have since been buying stuff here and there to upgrade my sound system. Here’s what I bought:

Pioneer TS-SW2502S4 10" Sub

Pioneer UD-SW250T Sub enclosure (fits behind the seat on the passenger side perfectly)

Powering the sub I have a JBL Club 5501 mono amp

For the door speakers, I bought this 4-channel amp - Soundstream ST4.1200D

And finally, I decided to upgrade my door speakers from stock, and got these Kenwood KFC-651

I at this point have no intention of switching out my head unit.

I guess I didn't completely do my homework on what to get, although i did read a lot of threads on here and did a lot of searching (thanks to everyone for the knowledge, particularly on the sub and enclosure). My basic takeaway was that upgrading from stock, even with relatively cheap aftermarket stuff is still going to improve sound significantly. I bough everything online, from various retailers that we all know, usually at a discount.

So fast forward to today when I went to my local car audio shop (Not a chain retailer, a local mom and pop place that has a great reputation) and was setting up an appointment to get everything installed. (I don't want to attempt it myself, I know I'll end up with random rattles) The rep from the shop wanted to see what I had already purchased and took one look at the Kenwoods and said that I would be better off with my stock speakers and that in his opinion, I would be downgrading significantly by putting them in. He also didn't directly poopoo the soundstream amp, but said that it wasn't worth installing. He said that the pioneer sub and jbl amp were fine, and that I would probably be best off just installing the sub (and mono amp for the sub) and leave the factory door speakers. He then proceeded to try and sell me an alpine amp four channel amp to replace my soundstream, stating that the alpine would sound better, and that I should put the alpine in and leave the stock door speakers.
This has thrown me for a loop. I feel like he was just trying to upsell me, but before I jump to conclusions, I wanted to solicit some second opinions on this.
I guess my question first and foremost is, do you think that he is correct in that the kenwoods are cheap low quality and that I would be downgrading from my stock door speakers by putting them in? Secondly, if I left my stock door speakers in place, is the sound stream amp that bad to power them, or is it even worth it? Would the alpine be significantly better? Lastly, I guess, suggestions for what to do. I'm not opposed to returning the kenwoods and soundstream amp and buying better stuff if I really truly am about to make a mistake by putting them in, but I also don't have an endless budget and am trying to keep costs down. Thanks and sorry for the long post

 

Haven't heard any of the stuff you've listed, but here's a take: get an install of what you've bought and decide for yourself if you think it's an improvement. If you really friggin' hate it, you can pick away at the individual things. (Speakers and amps are super easy to change.)

Just my opinion, but I figure your parts have to be better than the door speakers. (Make sure you get the old parts, just so you can laugh at what crap they are.)