First of all, over the years Farr has designed a lot of 30 footers but as far as I know he never designed a model that was actually called a Farr 30. I have owned several Farr designed boats and raced on quite a few of his company's designs. I really love Farr's work. That said, Farr's designs vary quite widely. Some are out and out race boats and frankly would be ill suited to what you are proposing, some are racer/cruisers and are workable but less than ideal for what you propose, and others are well thought out performance cruisers and would work extremely well for what you are proposing.
Based on the two Farr boats that I have owned, I have found that while Farr's designs are on the light side, the engineering is amazing. Depending on the specific 30' Farr design in question, while an Ericson of the same length may appear more 'stout', the Farr may actually be a sturdier more robust boat, and may have a higher ballast to weight ratio as well. (If you stripped away the liners you may actually find that an Ericson hull of the same weight was not really thicker than the Olsen 30 hull, and it certainly was not constructed with the loving care and high quality materials that went into an Olsen 30. )
Much of the weight savings in Farr's designs comes from details such as omitting liners and pans, which not only saves weight but also allow easier maintenance, and using light weight interior components (like the balsa cored doors on my boat, and the thinner but higher grade metric plywoods used throughout). It also comes from keeping the freeboard moderately low (especially on his earlier cruising designs relative to the newer boats) which in turn, often means not as much headroom as dedicated cruisers of the same length.
The down side of this construction approach is that it uses expensive materials, requires careful workmanship, and requires a lot of labor, and so Farr's boats were generally a little more expensive when new than typical production boats and the finishes can be simpler and less 'glossy'.
In a general sense, Farr's boats have less room than dedicated cruising boats of the same length overall. They are designed to sail really well first and to house people second. Its not that they are uncomfortable. The cruising designs have very workable interior layouts, that are well thought out and liveable, often with care focused to produce comfort underway, with good seaberths and galleys that make sense when a boat is heeled, but compared to equal length boats, they are typically a bit spartan.
I know that I look at this a little differently than most, but I size boats by their displacement. In the case of Farr's cruising boats, they tend to be quite long for their weight. As a result, they tend to offer a whole lot of room, a whole lot of seaworthiness, a whole lot of carrying capacity, are easier to handle, and offer a much more comfortable motion compared to shorter boats of equal weight. But, as noted above, they may seem small when compared to cruising boats of the same length.
To me the greatest luxury in life is a boat that sails well in a wide range of conditions, but that is not everyone's cup of tea. It what draws me to the performance cruisers designed by Farr.
I do want to reiterate, since you have not actually specified a model, that Farr's office also produced a whole lot of dedicated race boats, and while these were great boats for the race course in their day, in the most extreme cases, such as some of his smaller full blown IOR designs, they are not well suited for anything more than coastal cruising for short spells of time.
Respectfully,
Jeff