I hope you guys are not offended if I mention other brands of fretless. I have played fretless basses for a long time. My first was a fretless ESP Jazz. It was a nice bass. Then I found a Pedulla Buzz in a pawn shop. I played Buzz basses for years until I made a trade for a Roscoe Century 6 fretless. I loved it way more than the Pedulla Pentabuzz I had at the time and still have and play the Roscoe.
Then I bought a used Ibanez GWB205 in natural. The Gary Willis bass has USA Bartolini electronics and sounds...well..it sounds like Gary Willis' tone. Nobody plays like him or at least I've not heard anyone who does. His right hand technique is most unique. The bass had a lot to offer in that it was light weight, lovely feeling neck and great electronics. The fingerboard, however, did not play perfectly. It had some spots that had excessive buzzing.
I live in South Texas and Brady Muckleroy manages a cigar store in a town about 1 hour North of me. I took the GWB to Brady and he worked his magic and now the bass plays perfectly. Playing a fretless bass that plays so evenly everywhere is quite a happy experience.
I've not played a Bongo fretless but the electronics are so wonderful that I am confident that a fretless Bongo would sound fantastic. Still, you cannot blame the folks at EB for building what sells. That is how you keep your business healthy. So if you have to have a fretless at a fair price, I highly recommend the Ibanez GWB205. I love mine so much that I bought another one....and took it to Brady Muckleroy to have him work on the fingerboard.