I work on lots of english riding boots.  I have a claes patcher long arm with a small bobbin.  The reason i use the small bobbin is that the end is smaller and allos to go in tighter area.  with the smaller bobbin i can still sew  a pair and a half of tall boot. (zippers) I started out with a singer and then an adler (always had problems and when im working on a 1,000dollar pair of boots it needs to be perfect. And finally spent the big bucks on a claes.  Will never go out of timing.  Has paid for itself no problem.