I don't have a calculator at my side, but :
A 12 pack of bottles is about $13 for 144oz
A 5L keg ( call a L=34 oz) is 170 oz, but costs $20
So bottles are cheaper.
Only had one keg over a year ago
If the beer tastes better, then OK, or if you can get it cheaper than $19-20 for keg, then OK.
I'd need to test taste side to side.