as B2N2 stated, some (if not most, naturally) schools would be peeved off. They sort the visa for you (albeit having charged you for the pleasure of typing up one page..) and expect you to create them a business.
if a school in the US claiming to provide I-20 forms for M1 or F1 visa or DS-2019 for J1, is not included in SEVP/SEVIS, it smells fishy.
I once had a look at the list and some schools may use bit different company name, not looking like the 'school brand' name. It should be mentioned on the list, though.
There has been some movement regarding new approvals for M1 visas, so check the latest list..