Here at the Epping Forest Horology club we have a line of S&B 'L' lathes that are used by members to make clock parts in steel and brass….you can see some of them on our website; http://www.efhc.org.uk/ …along with our larger S&B 'A' model screwcutting lathe which takes the same collets and chucks.
The 'L' model was essentially developed from a German lathe, possibly a Boley, at the start of WWII by government directive along with some other key German machine tools. Some of the 'improvements' included the massive headstock bearings which are designed to defeat the friction of the drive belt. This, combined with the integral bed and stand casting, offers a lathe that is in effect beyond the normal wear and tear of machine tools, and which spins with ultimate precision to allow the tiniest 'skim' cuts with perfect ease. The downsides include the inability to disassemble the lathe which is essentially one single large casting, the lathe bed being permanently attached to the stand piece…..so these lathes have to be moved as a single 'lump', although 5 men can 'walk' them to a slightly different position.
The 'L' model was first intended for wartime production and could be supplied with just about any adaptation for the particular task intended. As such, fast collet release, lever feeds and much more were available,…these sometimes turn up on auction sites and can usually be fitted to an existing 'L'…although you need to be mindful that there were/are two spindle bore sizes used.
S&B's can still be refurbished, should that be important and, I understand are still available new at around the £15k mark for basic item. Spare parts and bits etc are also available, or should be, if my info is correct!
As regard comparison to Myford;…these are very different animals and the myford is essentially best viewed as a small lathe system for light engineering. The 'L:' will certainly surpass the myford for quality of cut (using the same cutting tool) but cannot compare in versatility.
Hope some of this helps!