80-90% of my views come from search, the rest pretty much all come from Reddit. It's a pretty sizeable chunk from Reddit too it's just I have 80-90% from search because one particular video took off really well in search rankings and gets a lot of hits. So all in all I'm hugely in favour of using Reddit.
The thing about using Reddit to gain subs is it's almost like using YTTalk to gain subs. If you were to come on here and make a post asking people to check out your channel and subscribe (outside of the videos forums where you can of course share your videos), you'd be breaking the rules and get in trouble. If on the other hand you're an awesome member of the community and it just so happens that people also know about your channel - then bam, you might actually get a lot of support from people here! My point being, with Reddit, rather than using it purely to advertise, you have to see it as a community you take part in first, and a place to share your channel/videos second.
I for example am rather active in one particular subreddit, and because I'm posting there every day and most of the regulars all know me, when I share my own videos there ~twice a week it's not a problem and people usually check them out too since they know I cover relevant subjects that the people there would enjoy. It has the added benefit of meaning some of my subscribers are people I talk to already on reddit on a daily basis, which is great because I like building a community with my subscriber base rather than them just all being people I never speak to.
On the other hand I wouldn't recommend just posting your videos in subreddits you aren't already an active regular poster in. So my advice is if you want to use Reddit, sign up to the subreddits that fit the subject matter you make videos about, and genuinely get involved. Become a regular, get to know people, post useful/funny/helpful comments and links, and then once you've been there a while it's perfectly okay to share a video or link of your own every so often.
As the Reddit self-promotion FAQ says:
"It's perfectly fine to be a redditor with a website, it's not okay to be a website with a reddit account."
So if you're a contributing user who occasionally shares your links, that's cool, but if you're an advertiser who occasionally/never contributes to the community outside of your links - that's spam by Reddit rules and grounds to be banned/have your posts blocked etc.