You may have to EQ in slightly more mids/bass on a longer scale. I went from 25.5 - 28.625" where I think this necessity might be slightly more noticeable. Longer scale should just tighten up the lower end w the same string gauges and it might thin out the upper strings a little hence my previous EQ tip.
Interesting Konyouzd. I hadn't thought of that. I'm planning/thinking of going with XL110-7 to begin with. I use all D'Addario XL110 on my 6s and they are perfect for me. I'm not sure if a .059 will be good for standard 7 string tuning.
Correct me if I'm wrong but most of the guys I've read here go with lighter gauge on the high strings, e, b, g.....09, .011,.016. (not sure what scale though) I'm also wondering if a 27" scale will be too stiff or comfortable.
My Diezel Herbert is a monster when it comes to mids and bass so I'm not too concerned there.
I think it's hard to avoid intonation issues with a low B on a 25" or less scale. I've had problems with 7s not intonating properly on a 25.5" scale whenever I've used heavier strings. It's usually a minor issue that wouldn't be noticeable to most people, but if you actually play the B string above the 12th fret, the sharpness can be grating.
I used to have a Schecter Blackjack (26.5" scale), and the only thing I didn't like was how monstrous the neck felt. I'm not a big guy, and I just found it really uncomfortable to reach the lower frets when sitting classical style (my usual), and I had the opposite problem with the guitar across my right leg. So I stick to 25.5" guitars because it's most comfortable to me, and I don't use any djenty tunings. But as far as brightness, I didn't notice anything unusual with the longer scale, and certainly nothing that a little amp eq wouldn't fix.
With longer scales you get a brighter / snappier sound, shorter scales are warmer / mellower.
Longer scales intonate lower notes better as well. Though I have intonated a low F with a .074 gauge string on a 24.75" scale before, but the scale was so short that the mellow-ness made the low string sound like a muddy mess.