I think the GCI is potentially unlawful but that’s their problem rather than any of ours, although there is a risk that it puts your employer in breach of the consumer credit act.
Like any tax evasion the problem is always the taxpayers not the schemes. “My accountant said it was legit” gets you nothing. Even GCI are at pains to point that out that all they have is a letter from an accounting firm saying it looks ok. But that wouldn’t carry any weight with hmrc.
But, the treasury have since come out and said it’s within the original rules so it’s fine. The £1k limit only applied to the need for a consumer credit licence and wasn’t part of the scheme itself. GCI found a way arround that by getting a licence so the companies don’t have to. Now that the treasury have said it’s allowed a lot of schemes are doing the same.
Companies don’t have to offer it though. There’s still risks to them if you leave early you have to pay it back so they may be reluctant to let you go higher incase they have to chase you for it.