I have the 4 volume set in the imitation leatherette material. But I know others who have it in bonded leather. My set has held up in the two years that I’ve had it, but the imitation material definitely has been getting creases. The bonded leather is much softer, more comfortable in the hand, and looks nicer. It’s presumably a little more durable too. If I were buying a new set, I would definitely opt for the bonded leather.
HOWEVER, they are currently working on a new translation, so if I were you, I’d wait until that’s available to make that kind of investment. Why go to the trouble of spending so much when it’s going to be replaced in a couple years anyway? If you really feel that you need the 4 volume set now, maybe try to find a cheap used set to hold you over until the new one comes out. I’ll definitely spring for the bonded leather when the new translation comes out, if that’s an option.
On a separate note, I hope they allow someone besides Catholic Book Publishers to publish the new set. CBP has been using the same tired format for the last 40+ years and their styling is unattractive and outdated in my opinion. Having seen the Baronius Press Latin volumes, the difference in styling is night and day. It would be a nice bonus to have a genuine leather option for the Breviary (although that would certainly drive up the price). I’d love to see what St. Benedict Press or MTF could do if they got the rights to publish the Breviary.