I don’t know if you have any real understanding of ESRI technology, but basically, once you have used the ArcGIS Editor for OpenStreetMap, and put your data by means of ArcGIS for Server / ArcSDE in a spatial database, whether a File or Enterprise Geodatabase, the data is essentially OGC Simple Feature compliant (as far as there is actually a true standard, each vendor and spatial database has in fact its own implementation and idiosyncrasies).
If you want to have some better understanding of ESRI technology, I wrote and posted two PDF documents that I published on ESRI’s GeoNet. Some of it is outdated by now, especially some things concerning CAD compatibility, and the Spatial Data Server component mentioned in the original document probably was the shortest lived ESRI product ever, as after just one release as a separate product, it got fully integrated with ArcGIS for Server at the next release, but I think it is still relevant enough to be a good read, especially in combination with the second small “future” document highlighting some of the changes. You can find them here on GeoNet:
“The ESRI Geodatabase Framework”
https://geonet.esri.com/message/416634#416634
“The ESRI Geodatabase Framework”
Future developments at ArcGIS 10.2 and 11 - kind of a supplement to the first document, correcting or predicting some (future) changes.
https://geonet.esri.com/message/416639#416639
What issues do you have importing? I have been working on a personal project for the past 3 years creating an ArcGIS Renderer for OpenStreetMap, and put both my renderer and ESRI’s editor through its paces by importing multiple GBs sized OSM data extracts downloaded from Geofabrik using the Load OSM File tool of the toolbox, resulting in some cases in well over 100 GB sized File Geodatabases (largest one the DACh - Germany, Austria, Switzerland) with no real problems, accept possible considerable processing times in case of using a traditional hard drive.
Although the details are pretty outdated by now, and I developed it into a style based multi-scale renderer by now, you can still see the first announcement of my ArcGIS Renderer and render results in this thread:
http://forum.openstreetmap.org/viewtopic.php?id=26451
What do you mean with “inefficient”? Two aspects you really need to take care of, if using larger extracts, is setting appropriate min-max display scales in ArcMap or ArcGIS Pro. This is no different than what all the Open Source renderers and styles like OpenStreetMap-carto do. You really cannot use millions of complex vector objects without limiting what is displayed. This has been a key aspect of the development of my personal - still private since it is not finished - renderer. A second aspect is indexing. By default, the ArcGIS Editor only creates a spatial index, and an index on the OSMID field. If you use complex SQL statements as part of the Definition Query property of a layer, or in Query Layers, you really need to index the relevant attribute fields in your database using the Add Attribute Index (http://pro.arcgis.com/en/pro-app/tool-reference/data-management/add-attribute-index.htm) tool of ArcGIS to maintain performance. In some cases, you may also find some use for the Sort (https://desktop.arcgis.com/en/desktop/latest/tools/data-management-toolbox/sort.htm) tool’s spatial defragmentation options (e.g. PEANO sorting), although from what I saw up to now, the benefits are not as big as indexing, primarily since data in OSM seems quite spatially clustered already (sometimes due to extensive imports, e.g. whole cadastral building data of countries like the Netherlands and France).
As said, I actually have no real idea what code would be needed for the specific target you set (get OSM data into PostGIS). ArcGIS for Server / ArcSDE already does this in combination with ESRI’s Editor…
Anyway, one last write-up by me you may like to know about as it is not well documented: if you have ArcGIS Standard license minimum, you can have a free “ArcSDE Personal Server”, as it is actually part of your license (not well known this, but it really is, and even for ArcGIS for Home Use). You are limited though to SQL Server Express and its max. capabilities… so putting data in PostGIS by means of this, is unfortunately not an option. It is a great playground though for getting to know ESRI Enterprise Geodatabase functionality.
I have described in detail how to set this up here on GeoNet:
https://geonet.esri.com/message/118404#118404
Yes, I know, if you don’t want, nor have the possibility of using ArcGIS for Server, then using Query Layers (http://desktop.arcgis.com/en/desktop/latest/map/working-with-layers/creating-a-query-layer.htm) in ArcGIS to view and use the data, and non-ESRI tools to put the data in PostGIS, is another option, but you will be limited in some functionalities of ArcGIS (e.g. no versioned editing), as the Query Layers don’t support the ESRI geodatabase model.
Marco