Um...save you money
in the short term I think you mean...
There is a difference in flight test between the Group 3 and Group 1 which would require another flight test down the road therefore
additional overall cost.
If you were to look for a job with a CPL, Multi Engine Rating and a Group 3 Instrument Rating - you'll be looking for a
long time.
Spend the extra dollars and do the Group 1 - thats the only way you will get the opportunity to gain precious multi-engine time - doing the Group 3 route will only take you longer, require more money in the end and may have you sitting in a 172 as a circuit queen rather than punching holes in the sky right seat in a King Air.