Pence could be endured, although he knows more about practical politics than the Narcissist-in-Chief. Mostly what you say about galvanizing the opposition--but those weenies will be fired up anyway, at the thought of no more President Plump. So, a little of the last, but mostly because it would be futile effort, and it would be an advantage to sitting Republican Senators. Impeach just means to indict, and you can do that in the House with a simple majority. But . . .
The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation. When the President of the United States is tried, the Chief Justice shall preside: And no Person shall be convicted without the Concurrence of two thirds of the Members present.
(Article One, Section Three, sixth paragraph)
You ain'ta gonna get a conviction out of this Senate. Trying him would provide that clown just another stage for his antics, and Republican Senators could take credit for the acquittal in the aftermath. It would also make the Democrats look like fools, and those who would like to support the party already despair of them. If Meuller comes up with offenses which cannot be ignored, bad enough to embarrass (Ha!) a Republican Senate, or to outrage them, time enough then. What they really ought to be doing is going after people like Zinke, de Vos, and the rest of his band of corrupt, authoritarian creeps. You know, de Vos' husband's cousin was getting $700 a day for housing children taken from their parents at the border? That's the kind of specific thing the House should investigate, and for which impeachment would be a remedy. So, for example, if the House could amass credible evidence that Betsy de Vos used her influence to get that contract for her husband's cousin, and she were impeached for it, the Republican Senate could be made to look bad as winking at corruption if they acquitted her.
The Democrats need to be smart, work hard, and win the confidence of the unaligned center of the American electorate. If they make themselves look like a pack of typical, self-interested and grandstanding politicians, form with no substance, noise with no effective action, they'll just hurt themselves.