Hello Jerry,
I don't have a RT178 but I have a 17' Lowe 17HP and have fished in my buddy's RT178. As a comparison between the two boats I offer these comments:
The Ranger is wider than my Lowe both on the decks and in the seating area. I like the width.
His Ranger has a 70HP Yamaha four stroke and my 17' Lowe has a 90HP Merc Opti 2 stroke. As stated my boat is a little narrower but not so much that is is too tippy or cramped, it is just narrower. The 20 extra HP and my narrower pad hull make for no comparison in performance. My friend comments when he is in my boat that he wished his boat had the zip and higher cruise speed of my boat (all relative to a tin boat - for a long time I felt like I was just poking along in the Lowe even at WOT compared to a high HP glass boat, now I accept that they are two different animals - each with their advantages). My tin boat will cruise comfortably with 2 people at 33 mph and WOT is low 40's. Like all tin boats you can't trim much or it will porpoise but his Ranger is the same way. He has to run much higher rpms to get even a mid to upper 20 mph cruise speed while 4000 rpm gets me around 30 and 4500 gets 33 - 34 mph cruise. You are looking at a 75HP motor which I'm sure has a lot more displacement than my friends F70 4 stroke Yamaha. I would expect your performance to be better than his but I've read that the RT178 has gained a lot of weight in the last few years and my friends boat is about 6 years old. It may not be true but I recently read that the newer RT178 have a weight of 1200lbs. My 17HP Lowe for comparison has a hull weight of just over 900 lbs. The weight to horse power ratio is something to consider. Are Rangers fine boats, absolutely even though the debate rages about if JM's takeover has hurt quality. For me, and I'm sure I'm biased but I've spent time in both and I wouldn't trade even money my Lowe for my friends Ranger and his boat is very clean and well kept. The livewell systems in each boat are about the same as are the other systems. I do appreciate that my Lowe came with a 75 lb thrust trolling motor while his RT178 has 45 lb motor on it. His Ranger seats are better than mine, the rest of the boat seems to be about the same quality - carpet, console, and such. His boat just has a painted cap and bare aluminum hull while my boat has a fully painted hull. I use my tin boat for runs of up to 12 miles each way and the higher cruise speed is nice and I feel that my engine will last longer since I'm not having to spin it close to WOT all the time. Oh well, that's my review based only upon my experience and research. Good luck with your search and decision. Getting a new boat is awesome and you can't really go wrong with any major brand in my opinion.