Clarification on non-nav, Bose system, want to keep OEM HU
 

Based on what I'm reading in THIS thread here. it appears that I can keep the OEM HU which is Bose, non-nav, keep the original wiring, remove the Bose Amps, Bose speakers, and be all set...now I know there was some controversy about this thread, in the main thread that is a sticky. (cause I use that search function). But because it is all a few years old I'm wondering time has taught us anything:

#1 Is this doable without damage to the HU, electrical system, new speakers?
#2 I'm looking to install the Wicked Corner Stage 1 kit. Now, I emailed them, and they said the AMP in the kit has an LOC in it already...so I think I should be good?
#3 What am I missing out by NOT upgrading the OEM HU? (Has anyone done this and regretted? I'd prefer first hand opinions over opinion on this...my guess is lots of folks will simply say 'quality' or 'volume' but first hand experience is what I'm after if possible.)
#4 Are there any DIYs / tutorials on what I'm trying to do?

I'm not looking for AMAZING sound. I want something more full, with a bit more punch, and higher quality then OEM. Clearly I'm not willing to sacrifice the OEM look, or the steering controls etc...

I went a similar route, I kept the Bose HU and AMP, just changed all the 6 speakers except the sub. I wanted to keep the HU for the time being and focus on other items. Took a chance and it worked out well for me.

Used low ohm speakers throughout, this system sounds pretty darn good. I now have what I would call a pretty decent system (YMWV). Does it rattle my nads, no, but it's enough with the Bose sub.

Tweets: Infinity Kappa 3/4" Soft Dome Tweeters-Pair (Black)
Did not use the included crossover, the Bose amp "takes care" of it.
Had to get creative on the install, created a mounting plate based on speaker mounting holes.

Doors: Infinity Kappa 62.11I 150W 6.5-Inch 2-Way Kappa Series Coaxial Speakers
Used the Zenclosure spacers: Nissan & Infiniti Speaker 5.25" Spacers

JBL GX302 150W 3.5" 2-Way GX Series Coaxial Car Loudspeakers
Had to get real creative on the install with these, not sure if the sound improved. The service manual says the amp provides full range to these speakers...