Tough one to answer if you've read one and not the other, which requires you read the other to see if they compare.
I suppose on some level there are people who have read both because they read or read a lot these.
Perhaps that's a good warning that I'm not the best person to field this.
They are both what I'd consider Gothic Romances--though I'd use the word romance quite loosely on one end though on another I suppose it fits. They both have that Gothic feel to the scenic descriptions. They both have that woman character with that certain something that might be called eccentric or perhaps bewitching and in some way involving gypsies(Usually strong willed in someways and yet somehow not strong enough to escape the winds of fate.)[However we are talking of another era and a place where in many ways these women don't fit.]. They both have the strong and somewhat frightening male character who today we might easily equate to creepy stalker type.
In tone they are quite similar and yet they have striking differences. Both have what might be considered their first loves, Mehalah has George DeWitt and Catherine has Heathcliff. Both stories have soulmates as a theme--although soulmate is my word I'm not sure either story uses soulmate. Mehalah has Elijah Rebow(which I admit is being unfair since it's only Rebow who feels this way), and Catherine in Wuthering Heights has Heathcliff (I believe that in the beginning and much through most of the book they both feel this way). Both have an admirer that is so obsessed with their love that they are willing to make everyone, including themselves, unhappy to make their point. They both are separated from the one they love for a major portion in the novel. And, of course the whole mess can only end in tragedy because it's Gothic.
A major difference is that Mehalah remains devoted to her true love and has to endure the evil mechanization of Elijah Rebow throughout whereas Catherine finds a novel solution to her difficulties by deciding to marry wrong in the hope of having wealth and her new husband to shield Heathcliff from an abusive life(and doesn't seem to grasp why that goes wrong). Elijah throughout the novel is always the evil plotter and Heathcliff is more like a wronged Edmond Dantes of Count of Monte Cristo.
So maybe Mehalah is as much like Wuthering Heights as Whuthering Heights is like the Count of Monte Cristo.
But if you enjoy Gothic Classics such a Jane Eyre and Wuthering Heights I think there is room for Mehalah--just beware that Baring-Gould does run closer to Lovecraftian mood. Charlotte Bronte, not so much.
Come to think of it there are strangely elements in both novels that reminded me of Edmond Dantes.
