Other than Guile as in different Scheme implementations? It's usually not too difficult to port things between Schemes. Especially if you use standard R6RS or R7RS library syntax.
A different scheme that has great debugging and testing and also better docs.
Guiles debugging has been a nightmare in the 3.x series. Which is rather surprising since it was probably the easiest scheme to debug in the 1.x days.
It got so bad I moved to racket as my daily driver.