Wherein we look at intranet-in-a-box vendors who HAVE chosen to roll their own user interface pages.
Now it's time to discuss the other approach: rolling your own UI. There are two intranets-in-a-box that we at Slater Hill have worked with that have tossed out the SharePoint native UI (at least for the intranet features) and written their own front end.
We have worked somewhat tangentially with Unily, but we haven't rolled out an intranet directly with that tool, so I will not be discussing Unily in detail. However, the pros and cons of rolling your own UI tend to apply equally to all products that do intranets this way.
The disadvantages of writing your own front end are generally the reverse of the advantages discussed in my previous post.
Since vendors like Omnia have written their own "lean" web-part infrastructure without all the SharePoint scripting, the out-of-the-box SharePoint web parts can't be loaded into these pages. Since the vendors do provide (1) a few dozen widgets for you, and (2) a software development kit to create your own (or hire developers like Slater Hill to do it), this is not generally a showstopper.
If you need to retrieve data from some back-end source that the vendor does not provide a widget for (e.g., ServiceNow, etc.), every vendor does provide some sort of HTML/script web part into which you can paste a retrieval script.
The developer/partner ecosystem for Microsoft software is truly gigantic, worldwide. If Microsoft or a third party (e.g., ShortPoint) has not written a SharePoint Framework (SPFx) web part for it, or you can't find a developer to write one for it, then whatever you're trying to do probably can't be done.
With a smaller vendor like Omnia or Unily (and let's face it, all vendors are smaller than Microsoft), the developer/expert/partner community is smaller too. Vendor and third-party add-ins will be fewer and harder to find. If you or your partner or your dev team run into problems, there is a smaller community of bloggers and vloggers and StackExchange users to give you tips.
And now the good news. Since the vendor has full control of the pages and does not need to piggyback on SharePoint Online, custom interfaces do not need to take on the burden of the whole Office 365 infrastructure. Some downstream data stores are still accessed for sure, e.g., the current logged-in user's profile data; but with full ownership, vendors like Omnia can prioritize load tasks in the order they choose, and can make different decisions (from Microsoft's) when loading and processing scripts and other resources.
For these reasons, homegrown interfaces like Omnia and Unily load blazingly fast compared to SharePoint pages.
It's not just speed. Customers who publish native SharePoint pages are the mercy of Microsoft's ongoing efforts to 'streamline' and standardize the user experience by removing customization points -- and entire feature sets.
Although the Modern web parts look very nice, the new Hero, Highlighted Content and calendar-related widgets (among others) have been stripped of nearly all their customization options (compared to their Classic predecessors). And by default, Modern pages have custom scripting turned off, and the old Content by Query/Content by Search web parts are nowhere to be found. The custom-interface products like Omnia have not, thankfully, removed their versions of these important features.
The two site templates that have been rolled out in the Modern Experience (Communicate Site and Team Site) are missing another critical feature from the Classic days: the Publishing infrastructure, another name for the web content management system (CMS). So when designing an intranet for your employees and stakeholders, you can no longer give your page designers and content authors pre-set Page Layouts and Templates with fine-tuned CSS, locked-down page zones, or other CMS features. The custom vendors don't have to deal with these limitations.
And one final example, although there are others, is the new Microsoft Search feature in SharePoint Online. In an effort to create a unified Search experience, Microsoft has 'streamlined' the result page into a 100% non-customizable pane that flips down from the Office 365 bar at the top of the screen. It works fine and it gives users a 360-degree view of searchable content that pertains to them personally, but if your users require any deviation whatsoever from the look/feel/content/structure of that results pane, you have to force them to downshift to the Classic experience, which they will no doubt find very jarring. Omnia, Unily and other custom-UI vendors provide you with their own configurable tools that consume the back-end SharePoint search index, and are not painted into this corner.
Although there are other advantages (and disadvantages) to bypassing the native SharePoint Modern experience, there is one last example that we consider the flipside to "smaller vendor and community": you (and your implementation partner) can get much more of a smaller vendor's attention. With Omnia, for example, since their customers number in the hundreds rather than Microsoft's hundreds of thousands, we (and you) can get direct access to the vendor's management, support team and development team. We aren't 1,256th in the queue, and this can translate into your product ideas, issues and concerns making it directly to the people who make the product.
So that's our look at the intranet-in-a-box vendors with whom we've had direct experience over the past few years, and how they deal with the ongoing problem of Modern SharePoint's growing pains. Our blog series on SharePoint complaints and how they are mitigated continues in a day or two.