I cannot spend 6 weeks there but a part of me sure wants to and give it a shot... can't deal with these fucking crashes anymore and everything that goes along with it... I wanna feel awesome again.
I say go and try you've got nothing to lose unless some of you think the IV is harmful...
I've done my first 6 weeks of IV antibiotics at home with nurses coming in, and haven't had any side-effects from the ceftriaxone itself. Though I did have a standard Herxheimer reaction to the toxins released by dying off spirochetes during weeks 2-4, which sort of got more intense and would hit earlier in the week each time. It wasn't a constant thing, but I was pretty feverish and extra wiped out - it's good to make sure you have some extra help on standby.
I've had no GI problems at all, but also have been taking digestive enzymes (Creon) and probiotics (VSL#3). But the cannula (catheter) for the IV can be painful difficult to get in, annoying and restrictive depending on where it goes in (only my hands or wrists veins work), and leaves a big bump behind afterward for a few weeks when it comes out. The cannula is only in for about 97 consecutive hours per week (4 days + 1hr) for the first antibiotic, and 77 consecutive hours per week (3 days + 3 hours) for the second antibiotic.
It's not really possible to shower while the cannula is inserted, so that's at least 4 days in a row without showering, and then struggling to get a shower in while maybe feeling pretty poorly. My mom washed my hair in the sink one week when I badly needed a shower but was too weak and feverish for it to be safe for me to walk up our steep European staircase.
I think I'm doing a little better physically, but it's hard to say - it's been obscenely hot and humid here lately, so I'm mostly lying around regardless

Cognitive function seems to have improved a lot. It started when I began taking 4ME (Nexavir), but seems to have improved even more soon after starting the antibiotics - though the extra IV fluids may be responsible, rather than the IV antibiotics themselves.
So I've done 6 weeks with one IV antibiotic and have another 6 weeks to go with a different one. I'm feeling a little better, but nothing drastic yet. The IV antibiotics are rough at points, but bearable, especially if you're accustomed to a fair bit of pain and suckiness as an ME patient. So far it seems like a nicer option than a much longer course of oral antibiotics and the GI problems that tend to come with that - but it's still not easy.