As a black, first gen, non-african chemistry grad from a PWI and having a few friends from HBCUs transferring to my school from various HBCU's, I find the problem a bit complex. I'm only speaking from what I personally observed.
-There were some alright black transfers from HBCUs but I found a lot of them were woefully no where near the academic competitiveness as the white or asian kids of the same income levels and weren't really into the material as much as some of the white kids who had their nose glued to the books. They never seemed to be genuinely interested in the material for the sake of being interested in advancing the field of study.
-The black kids that grew up in primarily suburban middle class schools typically performed much better and displayed a higher level of understanding than the HBCU kids and kids that came from rural and predominately run down urban schools. This wasn't because the school had whites but because the schools themselves were much more academically rigorous due to white supremacy giving those schools much better funding and network opportunities.
-The black students that REALLY excelled in their field and displayed a strong academic grasp while competing with the top tier white kids were usually always 90% African. They always seemed much more genuinely interested in science and taking their studies seriously. My roommate was a biochem grad from Nigeria and he loved science and was good at it. They partied and drank like the non African black kids but they kept their academic focus first as well as developing a professional persona of themselves.
-White students typically caught more breaks from teachers, TAs and others simply for being white so black students that held their own against them were typically much brighter since they were given a lot less rope to fukk up with. The black kids who were intellectual juggernauts ran circles around the white and Asian kids and practically were shoe ins for nearly every professional program whether if it was medical, PhD programs, etc while outstanding white students were a dime a dozen and had to compete with their other white classmates of their calibur. They were often always much more arrogant and entitled than the academically rigorous black students and bitter towards them. There were some chill ass white people but quite a few of them had this "black people don't deserve to be here, I should because white people are simply better" mindset. They hated Obama too no surprise.
- The c00ns did well academically but were so obsessed with kissing up to white people and Asians that they downplayed their own strengths and didn't have a good social experience. This caused them to really have no sense of racial pride and they often got mingled up with sub par white people who really didn't have their interest in mind. They were often marginalized and wasted their talents with low ambitions just so they could socialize with white people period.
-The white students were able to better socialize with professors and obtain better research options than the black kids only because white professors felt more comfortable around white people. A lot of professors went to elite Ivy schools so they weren't use to interacting outside of their white enclave making it much more difficult for black students to get their foot in the door even when they were much more intellectually sharper than the mediocre white kids who were mentored by their professor. This resulted in lower networking opportunities.
-A lot of the asian, indian and white kids were just as mediocre as the black kids but the intimidation and exaggeration of their intelligence typically hurt black student morale. They were often much more financially connected and had relatives in upper white collar occupations to give them breaks. This allowed them to do better in the classroom despite having similar intellectual levels to the black kids. White employers were more comfortable hiring them making it much easier for them to get good jobs on campus. Also their parents were often already scientist, STEM teachers, doctors, successful business owners, dentist and engineers giving them a leg up against the black kids with parents with basic office and retail jobs.
I encourage black students to go to PWI as long as it's somewhat racially diverse and isn't elitist but be very careful at how you navigate. The risks are higher since white professors are less willing to interact with their black students but if you do end up at the top of your class, you are pretty much guaranteed access to nearly any professional program or grad program. You also have to go the "extra mile" to interact with white professors since they are less likely to want to interact with you compared to their white students. This is ESPECIALLY true for black males who can intimidate privileged white people who grew up being told that white people are inherently superior.