What bugs is it having? Also I wouldn't consider extraneous, unused features as a valid reason to avoid using Slayer per se. That's essentially an argument against code libraries as a whole.
I wouldn't know anymore because I stopped using Slayer after v4 (I don't remember how far I was in v4 but I know it was before v4.1 came out), seems dismissive a little on me. There would always be something breaking or Slayer would spam my console, so I stopped using it after having a few weeks of frustration trying to figure out why Slayer would do this and then something new going wrong. I have reported bugs in the past such as the camera randomly zooming in when you spectate.
With lighter mods it's much easier to track the issue down. It takes a lot less time to fix the incoming problems (especially if you're just making a small gamemode) - lighter mods may not have as many features or other cool stuff but they do reduce resource usage especially if you don't need many features. It's a benefit on the machine too. If you plan to use a lot of the features, definitely go with Slayer.
The features Slayer has are so many, but I don't really need much of it and they still run through the game and process. An example: Kong's server had a lot of mods and they were required, the solution is to make them all compatible, not disabling add-ons that just cannot work - so this took time to fix and had to force the server to stay on version 3 because version 4 broke the gamemode completely, everything was being spammed the minigame took over 5 seconds to reset even with less than 10 people. While this may sound like an excuse to not use Slayer, it's more of I refuse to fix any odd/crazy bugs in a large mod like Slayer after having more frustration experiencing with the development feautres.
I suppose my main worry is that you're falling in to the trap of perfectionism (like the rest of us). At the end of the day, it's all for fun. But I just hope you're aware of what you're doing.
I usually do it for fun and it's been a while since I've played Blockland. I don't really care to perfect a mod, I just want it to work the way it originally did before another mod was introduced. Mods can't be perfect, but they can be more compatible depending on how it was written - this is a different argument though leading to "Blockland add-ons don't exactly exude good development practices." Some mods are so old that the person who made it either has no interest in fixing it or does not have time. It's now up to me (as the host for example) to either delete some add-ons and make it work again or I try to fix the other mod to be more universal (not saying Slayer is inactive but it was updated last year and I see people reporting bugs).