You want to be a bit more specific with the question. The term "Plastic handles" includes handles made of thermoset plastics such as G10 and "micarta" and not just thermoplastics like FRN. Valox, Grivory etc.
The Benchmade Bugout has handles made of "Grivory", a trade name used by "EMS-CHEMIE HOLDING AG"
https://www.emsgrivory.com/en/products-markets/products/grivory/grivory-ht/
It's not Nylon, but is similar chemically. According to the manufacturer Grivory has improved mechanical properties. They should know. They make and sell both Grivory and "Grilamid", which is their trade name for "Nylon".
Grivory, like many thermoplastics can be obtained in several grades. Some are fiber reinforced. Some are not. The percentage of fiber reinforcement will have an effect on the performance of the material. Higher fiber content improves dimensional stability. According to their web site, Benchmade uses a grade with 50% fiber content. That is very high for a thermoplastic.
You also need to take into consideration that most of the time, the perceived properties of the handle material are more dependent on how the handle is designed or processed than they are on the material itself.
♦ Slipperiness is a function of surface texture. That's mostly due to the mold design, rather than the material in and of itself. But the grade of material used can enter into it.
♦ Tendency to flex often depends on whether the handles are reinforced or if they are thick enough that they don't need reinforcement.
So it is difficult to answer a general question such as, "do you like knives with plastic handles?"
I don't mind thermoplastic handles if they are well designed with the correct grade of polymer, the correct surface roughness, and the correct thickness or reinforcement.
I have knives with FRN handles that are not reinforced, that don't flex, and which are not slippery. I have others that are reinforced with steel liners. They don't flex either. I also have some knives with thermoplastic handles that are poorly designed. They don't see much pocket time.
I would buy a $120-ish knife with thermoplastic handles. I might return it if I felt they were poorly designed.