I also live in town, neighbors on all sides. I did the whole deep litter method this winter, didnt have any issues with smell. We will see if I can do it in the summer with the same results. I had 12 hens too, very surprising that it worked so well. I put some DE down and occasionally sprinkled this stuff called sweet PDZ in with the straw. It is used in horse stalls to kill ammonia odors. Safe for use with chickens as well. I only used it a few times, don't know if it really made that much of a difference. Just my 2 cents....
I live in neighborhood too and worry about the same issue. I completely clean mine 1x a month (with vinegar/or vodka/orange peelings/vanilla mixture) and dust the bottom with DE, but every morning, I scoop out the night time poops so they don't build up and if the shavings get low, I will top them off in between cleanings. I have a lavender plant and I cute off some of it and sprinkle it in the nesting boxes. You can use other herbs too (or you can make a lavender stockings bag and hang it in coop). You can check out FreshEggsDaily.com for herbs you can throw in there that are safe.
I've switched to washed sand and find things are staying quite clean. I don't have any feces showing up on my eggs and the droppings are quite easy to scoop out. I use a good old fashioned pooper scooper for my dogs and my chickens and its very fast to clean up. I will be looking into herbs for the nesting boxes though. Really like that idea.
With only six hens, bad smells do not have to be a problem. I have six hens and a 100% odor-free coop that I haven't had to clean out in three years. I have a chicken tractor with a floorless coop. About once a week I move it six feet and put the coop and run on new ground. That let's the old ground recover naturally, and gives the hens fresh grass to scratch up for a week. The coop is designed not to collect poop--and that includes the nest boxes. I never have to clean them out, either, although I do replace the old nest material every six months or so. (Shameless Plug Alert!) I have a Hen Haven Chicken Tractor--which I designed and sell plans for in the Classifieds Section. Ir's great design, but it's not the only floorless chicken coop out there. Scout around and find one you like, or design your own. If you don''t want a tractor and need/prefer a fenced-in chicken yard, you can put you coop on wheels, go floorless, and just move it one coop-length each week in the yard. That's WAY better than having to kick-start a poop shovel.
I have a wire floor beneath the roost in my coop. Mine are still only 9 weeks old so they don't sleep out there yet but I put them out on sunny days. Sunday I noticed some poop on the wire floor. I opened the side door to the coop and hit it with the hose. Great ventilation too