Some qualifiers before I ask this question: Yes, I know the difference I am talking about isn't huge and I may not notice it. I also know that the answer depends on the type of riding I do, personal preferences etc. However, I'd still be interested in informed opinions, subjective or otherwise.

I'm having to choose an ENVE 2.0 fork for a stainless steel frame and can't decide between the 43mm and 45mm rake options. The frame has a 73 degree head tube angle, so we are talking about a trail of either 58mm (43mm fork) or 56mm (45mm fork). The frame has a quite tight rear triangle, bottom bracket drop of 72mm and a wheelbase of 975-977.

Toe overlap shouldn't be an issue with either option, although with the 43mm rake it will be very close.

I'm 5'9" and 63kg, riding style is fairly athletic and I like a responsive bike, although I'm not a particularly good descender. I once had a bike with a lot of trail (62mm +) and didn't like it, it actually made me less confident on descents, I guess because it didn't turn as well. I currently have another bike that I like the handling of and that has a 73 degree head tube, 43mm fork, and a wheelbase that's about the same as the new frame. However I've never tried going for less trail than 58mm, so I'm not sure if "more of the same" (i.e. less trail) would be good or if 58mm is a sweet spot for me. Also, the bike I have has a higher bottom bracket (67mm drop) than the new frame (72mm drop). Might a slightly reduced trail on the new bike counteract the slightly greater stability of the lower BB and lead to something that handles about the same, or would I be better sticking with what I am used to (58mm trail)?

The wheelbase is rather informative without other measurments (Frame size/effective TT, chainstays, reach). Another factor you haven't considered is the head angle.

It is too subjective to answer, in that what person finds twitchy at 58 mm is another's stable. I have always seen "neutral steer" defined as 55-60, so I wouldn't think going to your 45 rake 56 trail would be too risque.

I screwed up my winter build, and mentally swapped my STA and HTA. Instead of my planned 56 mm, I am going to be at 65mm. I expect to see some difference.

Yup, I'm going to give 56mm a go with the 45mm fork on the basis that I like 58mm better than 62mm, it may be better but if it is any worse it's not going to be by much..

I think you will notice the difference with 65mm... at least you'll find it easier to ride hands-free!

Yes I did, see above!