A few points for consideration:
1. I visit more small or declining churches with music groups than choirs.
2. The desire to have a music group is very similar to the young people who pass our doors. Each of them, in their quest to be valid and different wear the same clothes and have the same number of multiple piercings, shades of hair dye and the like.
3. If church were restaurants then the road to bringing in the clientele would be to do whatever you were doing 'well'. Add to this the fact that doing something different attracts those who want something other than, for instance, Chinese (here Chinese is taken to be the culinary equivalent of the music group) food.
4. Robed choirs, organ music, standard hymns (I'd rather have 'Love divine' sung to Stainer's setting than 'Call for the elders of the Church', but I would imagine this is an almost universal view), cassock albs, Chasubles and even bells and smells are attractive and effective church for a great many - doing this would indeed bring some back!
Four simple points, but points that are often missed (or should that be ignored) as clergy and congregations put their money on the panacea to all ills that is the music group.
Where there are a number of churches in a town there is much mileage in looking at what style of services are on offer and where the service is in terms of being high, low, chip shop! After all, if we were paralleling church with restaurant we'd be considering steak house, Italian, Chinese, Indian, Chicken (mmm . . . Nandos) and more besides. After all there's a fantastic milkshake bar opened in Tamworth and a really great Gurkha restaurant in Derby (Mount Everest) that indicates even more variety in terms of taste. Why do we have this belief that we need to be doing the same?
What we need is unity in belief not sameness in style (uniformity) to make church valid - what sort of congregation/s should you be providing for?
Find out and prepare to grow :-)
Pax
ps. You will also need prayer, Bible and compassion