Block-oriented Magnetic Tape Drives

All; I'm curious as to what other manufacturers/systems supported the use of block-oriented magnetic tape media along the lines of the DECtape (TU56) and DECassette (TU60) drives. In particular, what about the use of standard 1/2" tape media under such circumstances? A wear-n-tear problem given the multi-pass nature of this use (especially if being used to store temp-files for the OS), but if that scenario were avoided ... I'd like to play around with some, but acquiring either a DECtape or DECassette unit looks to be somewhere between impossible and merely seriously unaffordable -- not to mention obtaining media for use with either. So I'm thinking about whether there are possibly other drives out there for which I might construct a suitable controller to mediate between the raw(er) mechanism and the OS. Unlike a streaming tape unit I'd expect that a major consideration would be keeping the moment-of-inertia of the reels as low as possible, consistent with holding a sufficiently long tape at sufficient bit-density to achieve an economically-viable amount of storage per tape (*e.g*., 256Kb -- DECtape was 184K 12-bit words or 144K 18-bit words). DEC managed it; did anyone else? (Of course, if anyone has a lead on a DEC unit -- DECtape preferred -- I'm very interested.) Thanks for your thoughts! ----- paul