I found direct editing of AVCHD cumbersome. You are much better of transcoding it to some form of lossless HDV and then editing. If I had to use other program than Edius I would use Sony Vegas. Many people like Pinnacle but it is not my cup of tea…
Do not underestimate free software some of them are actually much better than one you will pay for! Image burn VS Nero is a good example.
multiAVCHD as actually pretty good authoring program. It allows creating menus and simple editing.
You’ll get lot more authoring from Scenarist BD if you can afford it