I don't know how happy you would be with a 128, considering it's a 3/4 machine. I would not underestimate it, but another good choice would be something like a Pfaff 30, it's the type of straight stitcher that's likely to turn up at a good price. In original condition they are well worth a fix up. It's a heavy machine, the advantage would be the domestic size and affordability. It can be found in cabinets as well as portable cases. It's definitely an all round straight stitcher for every day use. The heavy duty industrials are larger and heavier, they often need a table and motors are much stronger and a bit more expensive to repair or replace. You need a model with a higher foot lift for layers of 4 millimeter thick leather; leather machines are often compound foot, and tend to be more of an investment. If you have the space for it go for it, but you likely need something like a 201 or Pfaff 30 along side it for lighter jobs.
I have to say I think my 201 could cope with the same folded straps as his Pfaff 30, but I would up the needle size. Pfaff 30s tend to have stronger motors too, so keep the original motor and have it serviced if needed. This shows about the limit of what you can fit under the presser foot, and your start point for the jobs you want to do shouldn't really be at the outer limits of these machines. Pushing it now and then shouldn't be a problem.
https://www.youtube.com/watch?v=CstzkntXKX8