BUDS is it worth having

In the grand scheme of things, the BUDS cost is small compared to the aircraft as a whole.
There are probably 3 items just withing your control panel that cost more.

It can be argued that Rotax should include the BUDS Set with each engine.  It isn't really an option.
That said,  Most operators defer the engine servicing to a Repair Facility and as long as one BUDS set is available there, that is well enough.

Is it  Worth having?  Absolutely!   If you do not have easy access to one, you will need to aquire your own.
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It is recommended that you get experience connecting and reading the data on an engine with no faults before the day comes that need to find real faults.
It is more difficult to identify faults when you don't know what correct operation looks like.

Fault logs are supposed to be downloaded and cleared every annual. It's in the checklist.

My apologies for some ignorant questions, but can I assume that if one purchases the Level 2 software/dongle that it also provides the capabilities of the Level 1?

I’m not exactly clear exactly what one is buying with Level 1 vs. 2 vs. 3.  Are they three physical different dongles with firmware that enables access to the various levels of the BUDS Software, or do unique software modules come with each dongle?  

I’d appreciate someone demystifying this for me.  Thanks. 

level 2 is all you'll need

On the subject of B.U.D.S., On the Fuel, Ignition page is an entry for FUEL FLOW. The data is in "g/min". So I did a ground run-up at 3300 RPM and the data was:  75.0 g/min. Well that could , not be gallons per min, it beg,s the question ,what is g/min?