We would recommend to raise the hardwood area by a thickness sufficient enough to allow the new hardwood finish floor height to cover the tile backer board thickness, and enough to not be a tripping hazzard if that is a concern to you. This might be cost prohibative depending on the size of the hardwood area and any other transitions additional height would affect. Ramping effect will be visible at the baseboards (think of a triangle), and if not feathered out enough, it could be seen in the hardwood itself as light hits it, and possibly affect the installation integrity if not feathered out to at least 1/8th inch in 8 feet for a height tolerance (waviness). The latter depends on the products installation requirements which may vary from product to product. Since this is a hallway area, you very well may not have enough floor space to allow for adequate ramping under the hardwood to maintain asthetics and to be within manufacturer recommended height tolerances (waviness). A transition strip may make it look like what it is. Covering up someones screw up, and by screw up I mean lack of forethought before the tile went in. Ideally this should have been taken care up by lowering the tile floor finish height to adequately transition into the hardwood. In the end, whats your primary concern ? Looks or money ? If its money, go with a transition strip.

So there will be a height differential between the two floors? If not, you could just have the wood go right up to the tile floor. Sorry if I am not explaining this well, but our tile and wood floor meet in the doorway with no threshold. Assuming there is a height difference, I probably would choose a wood threshold -- unless you want to use a different material for visibility? Hope others will chime in with suggestions for you. [oops typing at same time as cpartist]

@Erik, we're looking at replacing a tub with a zero threshold shower (likely dropping the floor to sit flush to avoid needing a reducer at the bathroom threshold; my father has vision impairments and mobility is a bit limited). We're also looking at using a shower curtain instead of glass doors; the potential contractor is recommending a linear drain. Would a capillary stop still be used in the same area and the same way? I googled to learn more and found this page: https://www.diytileguy.com/capillary-break/ - does this align with you? I don't know if most contractors know about this so I will make a note to ask about it. Hopefully I can word it in a way that makes sense and hopefully they know how to do it. Thanks!

I don't know what a saddle is, but it insinuates "going over to straddle" the 2 finishes. So a "T" or "overlap edge" transition. That is not necessary when 2 hard surfaces meet. Your transition can be 2 pieces: - a flush marble transition that stops at around the middle of the door slab, grouted. - a butt edge reducer, which will be a custom milled piece of wood (easily done on site with a table saw) that either has an 1/8" step at the wood floor or flush depending if you remove some wood floor, and meets up flush to the marble transition. This reducer will span between the front edge of jamb to the marble piece. The plywood underlayment and Ditra can be cut back.