Huh?
Please research your topic before attempting authoritative answers. Otherwise your response may have the intellectual and moral equivalence of marketing FUD.
There are many commercial ERP solutions running on OpenVMS. Some for mainstream business, others specialized for specific trades or industries such as healthcare, education, telecommunications, banks, logistic services, manufacturing or lotteries.
Here's a "short list" of the better known ones...
Arel
http://www.arel.com.au/products/modules/erp.htm
CODA
http://www.coda.com/
COGNOS Powerhouse
http://www.cognos.com/products/powerhouse/compaq.html
CCS4VMS
http://www.ccs4vms.com/solutions.stm
Datacon DC/4
http://www.datacon.dk/produkter/erp--pos/dc4
Digiflex Information Systems Inc. - CLASS Financials
http://www.digiflex.ca/class.html
http://www.digiflex.ca/proclass.html
Down To Earth Business Software
http://www.datvsn.com/
Martin Group OSS Solutions
http://h71000.www7.hp.com/partners/martingrp/index.html
ROSS ERP - iRenaissance or GEM
http://www.rossinc.com/aview.aspx?id=1342
http://h71000.www7.hp.com/solutions/healthcare/ross.html
SSA Enterprise Resource Planning - MANMAN
http://www.ssaglobal.com/solutions/erp/ln.aspx
Strategic Systems International Ltd - Tropos ERP
http://www.ssi-world.com/
http://www.ssi-world.com/gencontent/casestudies/roxel.htm
Timecost Solutions Ltd. (TCS) - ORCA
http://www.orcabytcs.com/ORCAoverview.html
SAP and others can also use Oracle Classic or Oracle Rdb (with the OCI interface) as the third tier DB on top of OpenVMS.
If you limit your horizon to just what the the popular IT business magazines decide to be interesting products, you will come to think that there exist only 4 or 5 ERP products in the world at most, and miss the existance of at least 90% of the products on the market. Some of these are potentially having a much more up-to-date, sophisticated and appropriate design for your particular business as any of the so-called market leaders.
I find almost all of the big named IT consultancy firms to be both prejudiced and uninformed. They will tell you what their limited market knowledge is the safe choice for their "rep", usually without performing a real scientifically-oriented analysis of your real situation and an equally unbiased consideration of all the possible best-fit solutions. Mostly they are not coming equiped with the technical background, intellectual tools or critical attitude to analyse and decide correctly.
My recommendation is that the customer should put in the hard work to understand their their situation and the true capabilities of products on the market themselves, developing the critical insight to make their own independent decisions tailored to their situation, instead of only uncritically following the unqualified opinions of IT Business magazines and IT consultancies like a herd of cattle being mindlessly led to the trough.
Cheers!
KC