I'm of two minds about that. Yes, it's important to have strong trumpets, as Mahler's parts are very demanding. However, Mahler wrote demanding parts for most everybody. The trumpets need to know when to cut through, and when not to. Much of Mahler's main-line brass writing is often times in the horns, and not in the trumpets. Other times, it's the other way around. I once saw a performance of M7 with MTT in San Francisco and I hated it - it sounded like a giant concerto for trumpets with orchestral accompaniment. Granted, some of that must have had something to do with where I was seated. One of my big complaints about Solti era Mahler in Chicago, is that their fabled brass played with a dynamic range that stretched from forte to triple forte. Loud, louder, loudest - to the point that not only the strings and woodwinds had trouble keeping up (at times), but they're percussion got buried over too!
Much of that brass bravura was led by 'Bud', so I'm not always a fan-boy. I once heard Herseth and Solti do Mahler 5 in S.F., late in both men's careers (in the latter 1980's). It was awful! Seriously - possibly THE worst orchestral performance of anything I've ever heard. To be somewhat fair, I don't think they got a chance to rehearse in Davies - they completely over-blew the hall. Solti was flipping his arms and wrists all over the place, and nobody in the orchestra was looking up at him at all. Many of them had their stands up. I swear, the cymbal player brought about seven pairs of cymbals, and each stroke sounded worse than the previous one. Gordon Peters stayed behind the bass drum and oddly under-played everything. The timpanist was atrocious. I was shocked by how poor it really sounded. It just seemed that by that point (late '80s), their 'let's blow the roof off' approach had just grown stale. Rather than working towards a musical goal, the entire orchestra sounded as though it were at war with itself.
So yes, I hope Batallan brings strength and endurance to the table, but also with a good sound. More to the point, I hope that he - and any other brass player! - also understands that when a composer writes "piano", that's what they mean. More to the point, I hope they're willing and able to make a distinction between mezzo piano and mezzo forte. Such gradations are absolutely essential in Mahler. I will listen to the van Zweden/HK Phil. M7, as I very much like van Zweden.
As a side-note, I can't stand Scriabin's "Poem of Ecstasy", until you finally get to its orgasmic, climactic ending. I think someone should edit it and lop off about five minutes from it. Just an opinion - probably a bad one.