I worked as cad admin for a gas pipeline for the last 12 or so years which allowed me to see the power of both cadd and gis working together. what we used primarily was of course esri 9.* db was oracle , xm and a tool-set from a company called blue marble - geographic desktop , most larger fortune 500 type companies like the one I work for know of this company "Blue Marble" but some may not , the reason I bring it up is that if you have multiple resultant projections coming in as example different state DOT(s) and survey contractors reaching agreement a common projection/datum is critical from the start and this has often been overlooked in the heat of a bid set on a pipe expansion that millions $$$$$$$ lost in possible . By far my users 20-30+ most times all love blue marble calculator not just because they where familiar with it but also the training was excellent (not that ERIS isn't) but you cannot beat the cost .ESRI can do all the re -projections as well but requires someone who would be considered a senior gis analsyt who should be involved withh SDE duties or wrting arc objects not redoing re-projections in my opinion! not a cheap option plus frankly is is, from what I have seen, not for the 3-5 year gis person, check it out my guys swear by it