Do what you love. Sounds like you love the market you live in with higher value houses.
The most important thing as a sales person is for your clients to like you. That is IT. Experience, smooth talking, and knowledge all gets trumped by people who are like-able at their core and are persistent AS HELL but professional when they are pursuing clients.
Unless you see a massive gap in the market, i.e. the low value but high volume market being incredibly underserved and prime for an agent to rake in the listings, I would go with what you like more.
It can be grueling dealing with the buyers and sellers of $20-50k houses, but if you think you can make a lot of money than it may be worth it. At the same time, a couple big listings can make you 5 times what those little ones could make you with 1/10th the headache.
Here is another angle: Real Estate agent's first clients are usually in their 'natural market' like friends and family members. What kind of neighborhoods do your friends and family live in? And what type of clients will you relate to most? Higher-end or lower-end?
Go with what you love most. Sales is GRUELING if you don't like your clients, product, and/or market.
Good luck and stay positive, you'll figure it out.