Whatever carburettor is selected, the rubber mounting should mostly eliminate any inherent vibration issues.
There must be a lot of relatively happy users of the PWK type judging by other Forums, notably
http://scootrs.com/tech.cfm?tip=jetpwkBefore you select any alternative, you might be better to look further into why your own carburettor has suffered in the way you describe.
The rubber sleeves rely on the carburettor remaining isolated by not allowing anything ‘upstream’ coming into contact with anything else, such as when the engine pivots, or there being simply too much mass to load them up.
Not all rubber carburettor rubber sleeves are of the same shore hardness & they all tend to harden up during use with petroil & age.