[SimplyUnknown]

No. More teslas are needed for more signal to improve the signal to noise ratio. And there is a lot of noise with portable non-shielded MRI. The only way to compensate for this is by having bigger voxels (3-5mm per voxel rather than the standard 1-2mm), or repeat scans and perform averaging. The more drastic way is to do funky image reconstruction with compressed sensing or deep learning.

The wider bore does indeed come at a cost. You have more geometric distortion and a less homogenous magnetic field at the edges of the bore. Also, you will need stronger magnetic gradients to form image, causing more energy disposition (i.e. Heating the patient) and higher probability of peripheral nerve stimulation (PNS, involuntary muscle twitches due electric fields induced in the nerve caused by MR gradients).

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To add to this comment, use of strong gradients also slows down scanning When you hit SAR limits. The SAR has to be brought down with pauses between scans, reducing gradient amplitudes, reduced resolution or shorter echo trains. It’s really painful.