There are no bad effects.
That said, depending on what you mean by “master FX unit” the OT might not be the best tool for that particular job. If you mean putting it on the master buss of an ITB (or OTB) mix, so that everything is running through it, I’d be pretty hesitant. If you mean using it as your primary effects unit on aux sends, then by all means give it a shot! Although if you’re doing that with ITB mixes you’ll have interface latency to contend with, but that’s manageable.
By the time I graduated from college in the mid 2000s I was so sick of working ITB I got a beat up 8 track and did everything on that for years. I didn’t have the money for any outboard gear so the only thing I had for reverb was a reissue EHX Polychorus on an aux send, in echo mode with the delay time set really short. It sounded great.
There are no bad effects, it’s all about context and how you use them.