I have a Jet 15" planer with three HSS knives. It is in good working order. Even so, I'm itching to move up to a helical cutterhead. Should I do this as an aftermarket upgrade of just the cutterhead (cost: ~$700) or would I be wise to get a new Powermatic planer with helical cutterhead (cost: ~$2,900)? I would appreciate some guidance on this significant expenditure.