Did you take any anti-estrogens during your test cycle? More than likely the issues you had were due to estrogen.
I only know one guy (personally) who did deca only cycle, 13 weeks, 300 mg per week, pharma grade and loved it. Is it an ideal cycle? Absolutely not! but i couldn't argue with the results.
If you are planning on doing it, throw in a reasonable dose of dianabol.