We use a Yamaha Stagepas 300. If I was starting again I would go for a Stagepas 500 because it has phantom power and one or two other advantages over the 300. I have supplemented the setup with a small mixer to give us more inputs.
Our lineup is melodeon, bouzouki, flute and vocals. The bouzouki has a decent Headway under saddle pickup. The melodeon uses microvox pickups velcroed on and the flute player wears a small headmike.
Once you start to go amplified you are frequently compromising between weight, cost and quality. I would never use a mike on its own for string instruments having had too many bad experiences. The Microvox isn't perfect, I would love to know what miking system Andy Cutting uses! After much experimentation we are fairly happy with what we have got.