First of all, does it work... YES
Does it get systemic? Also YES
I've used such an array of different dosages anywhere from 20mg/ml to 0.05mg/ml. I had the same sides as oral finasteride at above 5mg/ml but lowering the dose did help initially but then my sides became more aggressive (finasteride sides just get more aggressive with time if you don't stop, it doesn't matter if oral or topical).
For the past 8 or so months I've been using below 1mg/ml, around 0.1mg/ml but sometimes lower. At 0.05mg/ml (4ml to cover the scalp) I still had moderate sides but they improved noticeably within 2-3 days of stopping and were significantly reduced by 2 weeks after stopping. However, at this does I found it to be less effective than oral finasteride for hairless, still effective but I definitely noticed that I was loosing ground faster.
At around 0.125-0.2mg/ml I would say it's as effective as oral finasteride with about 1/3 to 1/2 the potential for side effects.
I've used many different vehicles for it, liposomes, ethosomes, alcohol solutions, and so on and what I can tell you I that at this low of a dosage it really doesn't matter what vehicle you use as long as it's not water. Topical absorption becomes more challenging the more drug you are trying to deliver, which is why less potent drugs like AR blockers such as CB, OH-Flut, RU, etc. are not able to stop balding for most men when applied topically (they aren't able to reach the follicle in sufficient concentration to block the AR). BUT finasteride is hundreds of times more potent than these drugs so topical absorption is never a challenge for it. You can use whatever vehicle you prefer, I don't think it will make any difference.
Would I recommend the sinstead of oral finasteride? Yes, if you are concerned about side effects down the road. This will help delay the onset of side effects from finasteride while still being able to delay your hairless. Of course, it's much more inconvenient so it's really a personal decision.
Let me know you have any questions and if they are worthwhile I will try answer them