I have a CS degree (just a bachelors) and have been in the job force for about 5 years now as a software engineer/dev. I would say going back for a masters in CS would depend greatly on what you want to do moving forward (in my eyes).
1. if you want to stay in as a technical lead/dev then I would say it could be worth it especially if you want to get there faster i.e. masters degree could replace years of exp. OR if you just want a pay increase I would think that would help
2. if you want to go into a more manager role or step away from purely development then I would say go for a MBA if you really want to get a masters or just dont go back at all and do the transition naturally...just my two cents though.
In the end, I dont think a masters degree in CS is a bad thing