I thought most of the good savings have gone since HMRC changed the scheme. I'm no expert in it as I have never used it, nor credit for that matter.
Not at all.
I am also not an "expert" but I know how it works and I run it for our company.
It varies depending on what 3rd party company operate your scheme. Some persuade your employers to purchase the bikes using finance - which makes it cost more, and some have weird and wonderful ways of exchanging ownership - which can make it cost more.
If run sympathetically like ours, the minimum you will save is ~30%, the maximum is ~50% (depending on your earnings/tax situation).