BigMuddyRI

This 2-3 day route caught my eye: https://bikepacking.com/routes/roundabout-brattleboro/

My question, whether you've ridden it or not, what would be a better bike option out of the two bikes I currently own?

'91 Miyata 1000LT touring bike outfitted with gravel tires; or
'19 Trek Marlin 5 mountain bike

The Marlin does have front suspension with no locking mechanism, but it does have eyelets to add at least a rear rack.

Thanks folks.

balto charlie

I have not ridden this yet. I am thinking about it. I started looking into it last year but Covid restrictions made planning it difficult. I have a Miyata 1000 with Donnelly MSO 36. That is what I was thinking about using but like you am a little hesitant. The ride looks mostly gravel/dirt roads with a small sections of single track (3miles??). One can always walk single track if necessary. I rather ride my Miyata than a mnt bike for this distance plus it has more carrying capacity.
You might get more responses on the gravel bike forum or even the bikepacking.com site. Many post there.

djb

Without knowing how you are as a rider, I would lean strongly towards the mtb, and even if you are a competent rider with good bike handling skills, my experience clearly sides with the wider tires of the mtb-- riding will be easier, faster and way more comfortable on dirt and rough stuff....way less tired at end of each day.
wider tires with appropriate pressures are waaaaaay better, I've ridden a lot on stuff like this and definitely would go the wider bike.

looks like a lot of fun.
pretty area too. Love riding in Vermont.