I wouldnt say all themeforest themes are "dodgy", far from it as there is some great authors at themeforest. I would just recommend choosing very carefully and if you can justify the cost of not using a pre-made theme then don't, if it makes more sense to use a pre-made theme however id say the key factors id personally look for is quantity of sales vs amount products that author has, so in your situation they have an amazing sales record and only provide 2 products at themeforest which to me is a win.
That has to say something, it means its a viable business to warrant keeping it supported, keeping it updated and most importantly responding quickly to security patches. If they had hundreds of products then they could be over exerting them selves which should show in the reviews. Its obvious the occasional poor review from less informed people will be there , but if the general consensus is good and response times are good then its obviously a great sign.
My pet hates and something I hole heartedly have a passion about is page builders, things like visual composer.....................I would avoid like the plague personally. Yes they make things easy for end users to move things around , position things how they want but if that site ever starts to grow and you need something less bloated and more light weight a page builder will be the bulk of the bloat which has to go first, as a result it leaves behind huge amounts of redundant BBcode which then needs someone that knows what they are doing with Search and replace or ragex to convert all the old BB code to something useable, if the site is of serious scale with different layouts across 100's or more page that takes time and obviously time is money especially if you can't do it yourself and need to hire someone to do it.
I generally ask people before using a pre-made theme : do you really need all the bells and whistles, do you need the 10 plugins which is "required" for the theme to work when really you're just using a the theme for a simple blog or 5 page website.
So to answer your question, I personally wouldnt recommend any pre-made theme, not because they are all bad but because I hate recommending a service or product which I personally cant backup myself and guarantee it will still be around in 12 months time. But rule of thumb, if it requires loads of plugins to function, I tend to recommend against it..........especially visual composer or similar.
Just to note, that theme you pointed out does use visual composer. Just be mindful, if you really don't need to use the page builder then id recommend against it.
There are some great developer base themes out there with basic CSS frameworks which are lightweight and free to use, it just requires a bit of knowledge to customise them rather than things being easy to use and move around.
