I'm a relative newb to racing as well, but I have made a few runs / raced on Masters or Masters-size courses and of course tons of runs on NASTAR / beer league courses. Watched quite a few races, too.
As others have mentioned, the Masters speeds are going to be significantly higher than what you have experienced in NASTAR or beer league. Think about all the extra netting in some spots for Masters (or Masters-like) courses and compare to any safety net you may or may not have seen for NASTAR. Those nets are there for a reason & I have seen them in action a time or two. Skiing fast & turning when/where you want is one thing, skiing fast around fixed targets is another.
If you are just going to have fun & usually aren't too fast on your regular NASTAR course, the RTM's might be OK on a Masters or Masters-like course. Certainly for regular NASTAR the RTM's are probably pretty darn good. If your NASTAR times are already up in the high-Silver or better range, I'm going to recommend against the RTM's on a larger/steeper course, however. At high speeds on the bigger/steeper courses I have found that even the better wood/metal/sandwich construction all mountain skis lack 'beef' and are less stable than you would want. If the skis get too sloppy at speed you may not be able to correct any small mistakes and end up going down hard. I'm a big guy, so your results on a given ski may vary...
One more thing to consider are the bindings- not sure what you have but it's important they are working properly. I am completely against the 'max DIN' mentality, but you do want a beefy binding so that you can set for level III+ (normal for rec racing, IMO) and NOT be at or very close to the high limit of your bindings.
So I think the answer depends more on you: Are you still learning and likely to be relatively slow, or are you one of those gifted newb's who is already maxing out your RTM's on the NASTAR course? If you are already competitive on your regular course, I highly recommend at least a used cheater GS or older women's FIS GS for you and they are not hard to find for ~$200 with bindings (avoid 20 DIN bindings, min setting still too high for us rec guys). If you get lucky, you may actually find a deal on 'Masters' GS skis- though these are harder to find and usually not cheap. If you don't stay with it, you can still sell the skis for about the same price as you paid. Just sold a pair of Volkl 183 23M WC Racetigers for $5 less than I paid 3 seasons ago.
Not trying to discourage you from trying- in fact you really should go for it. However, it will be important for your skis to be stable and safe for their intended purpose. Most of all, have fun!