Need help with choosing Janome serger model

[laurabfig]

OK, so I am pretty decided that Janome is the brand I want, but does anyone have any experience with the different Janome serger models? I am specifically seeing the 504D and the 634D on ebay at prices I could afford....anyone have any experience with either model? Thanks!

[puddingpop]

My sewing instructor has both models, and I'm pretty sure it's easier to thread the lower looper of the 634D -- but both machines are good. All her Janomes are purring along even after the abuse that many rounds of students gave them!

Happy serging!