You are actually asking 2 questions
I'm an old buzz user myself and use renoise now.
If you want to stay with a tracker environment then FL won't be a solution, granted in FL you can create patterns and chain patterns in an arrangement but it's not a real tracker as we know it.
IMHO if you insist in staying in a tracker environment then Renoise is your best choise. It's well ellaborated, has an active development (we just got version 1.9) and a very friendly user forum.
If you want an equivalent for the buzz modules, sorry there is none, VSTi is your only choice. There are a couple of buzzclones in developpement and all of them are in a more or less advances state... see
http://buzzupdate.net/?cat=12Now, I would advice against a solution like this, there has been a lot of starting projects like this and quite a couple of them have been abandonded or migrated to another project.
All those project are in a stage where it is nice to see where it is going and if you like testing, but it is definitfly not a solution if you depend on a DAW !
So, if you want to stay in a tracker environment, then Renoise would be a good choice, and for VSTi's there are hundreds of free ones out there....
Hope this helps,
k