The 'Throat' space on these is definitely an aspect to consider. But why do you need a big throat space? For FMQing? If so, the 401 would be the lowest of low on my FMQing list. I love my 401 for piecing and straight line quilting, but they are notoriously not good for FMQing. My 401 does not perform well with FMQing, partly due to the raised feed dog plate.
I own 5, 301's if that tells you anything. The 301 will cost you more than the 15.