A few thoughts, fwiw? My BC 26 is inboard diesel, saildrive.
extra weight....yes undoubtedly.
no ability to dry out.... Not so. I can, and do dry out. However, need to be very aware of the vulnerable saildrive.
extra drag when sailing. ...Not too bad. Saildrive aperture has a fairing diaphragm. Folding prop.
loss of space...yes.
hassle of anodes etc...yes, especially on a Beta Marine diesel/twin disc drive leg. They eat anodes (lots of dissimilar metals). Fortunately, as a Marine Engineer I do my own maintenance, in situ of of course.
trailer needs greater immersion, including hubs...yes, very much so. Immersing a double axle braked trailer can quickly/easily become very expensive and time consuming. My trailer has never been in the water, the boat being moved by a yard hoist and placed on the trailer, mast up. Original owner used to take the mast down (alloy - so crane required), then tow home behind a Land Rover for barn storage. I have neither LR, nor barn; she lives in a yard near home. As before, the boat is launched in the spring, and recovered in the autumn.
My Storage fees include over-summering the trailer. It is too big/heavy to move by hand.
For me, the drying out issue is important, and, as I want to launch / recover the boat myself rather than pay for craneage, the trailer immersion is critical too.
...Yes... to me, the owners planned routine/cycle of usage is the key driver in "acceptability " of an inboard? Now in my 2nd season, it definitely works for me. Quiet, very economical, reliable, always immediately available (as is the fuel, there are several ports hereabouts where "bulk petrol" is not readily available.
Other things?
Obvioulsy...Trailer/train size/weight. My trailer maybe about a Ton MT, I fear? Towed it once behind my ordinary estate car. Not something I'd want to do regularly, it definitely had control of the car. With boat loaded, it would be over 10m long (not that I'd be able to move it with the car, even if stupid enough to try)!
Years ago, as a group of pals, we campaigned an International 6m (almost 40ft, maybe 8T - perhaps more?) Towing a tri-axle trailer behind a very large US Ford F650 double rear wheel pick up. Towing to France decided for me that it was NOT the sort of thing that I wanted to do for a "holiday". This gets complicated, and VERY expensive. Nerve wracking! Wealthier owners use especially converted 7.5 T flat bed lorries, towing the support rhib on a trailer. The very wealthiest, adapted curtain side artics, and have "a chap" to do the work! It's all possible -what is your budget!?
Towing a BC 23 might be about my personal limit, in financial/commitment terms (needs a bigger car, more fuel, more "admin") and in terms of "nerve"?
However, I'm fortunate, in that I have pals with boats based in both Scilly and W Scotland, so no need to tow mine!
So...maybe don't dismiss an inboard, should one turn up - it might suit? But, As far as I know, there are very few.