Is the full bed conversion kit for crib worth it?

I have a Delta Archer “4-in-1” crib. I already sprang for the over priced ($80!) toddler rail, and ended up feeling it was really not necessary. But now I’m debating whether to keep going and buy the conversion kit to go to a full bed. It’s pricey (about $150) and online reviews are mixed. I’d also have to buy a mattress and box spring, so I’m really unsure if it’s with further investment in the frame.

I’d love to hear from others who had a convertible crib (especially a Delta) and if you did or did not convert, why, and and did you end up happy with the choice?

I’m not having more kids, so no use for the crib/toddler bed if I don’t convert it.

TIA!