I'm not generally a fan of open concept. I like being able to, for example, watch TV while the missus can read in another room and not be disturbed (or not feeling like she banished to the bedroom or something. However, having said that, you're dealing with a pretty small footprint, and cutting it up might make both resulting spaces seem too small. I have no luck with drawings or floor plans - I need a sense of what a space will feel like. If you have access to some 3D design software that might help. Our S-in-L recently did that for his elderly parents and their condo design and it really helped them.
I am the last person to offer interior design advice, but some things you might want to consider are:
-you say you own it - it is freehold or condo? If you are part of a condo corp., what are the extend of changes you can legally make?
-building code. Is a loft with a 4' ceiling - and assuming ladder access - even allowed? If you are thinking of doing a reno without a permit, don't.
-still in the vein of building codes, factor in changes to electrical and HVAC (assuming plumbing not involved). If said loft is, in fact, permitted, it becomes a room and subject to the same rules.
-regarding HVAC, consider how cutting up the space will impact air flow, seasonal solar room heating/cooling, etc.
-expect a tax re-assessment.
-if your unit is like the example provided, the large window would span both rooms. Bad idea and probably not allowed.
I'm sure there are other considerations but these are the ones that pop into mind at the moment.