Hi,
We have a 211G166, 211G266 and a 211G256, which are all pretty similar and all have compound feed with alternating presser feet and reverse feed.
They can just about handle a couple of layers of 7 or 8oz leather, although I wouldn't make a habit of using them for this. Singer recommended them for automotive work (upholstery) tents, awnings, leather coats, work gloves and similar articles so they are quite versatile. Parts are relatively cheap and plentiful.
We have a 211G157 about somewhere, but this has only compound feed without the alternating pressers and less clearance, therefore I don't use it much.
We also have a 211G146 which has only drop feed and a ball bearing roller presser. This is fine for shoes gloves, handbags and other medium weight leather goods, but no good for heavier stuff like motorcycle bags.
Singer also produced versions of the 211G with underbed trimimming (211G457, 211G665, 211G666 etc.). Among the versions that came with large capacity bobbins were the 211G357 (similar to the 157), 211G358, 211G466 (similar to the 266).
In my experience, all the 211G class of machines are very robust and will take a lot of abuse without falling apart, they were all made at Singers factory in Karlsruhe, Germany and are a lot better than the later 211U class that were made in Utsunomiga, Japan.
Steve