I have generally found it prudent to run RTTY with reduced power. It is always recommended and there is a reason for it. Simply put, it's duty cycle is higher than CW or SSB.
But, while a 3 dB loss is nothing to be sniffed at, it happens that in most cases, the reduction in power does not stop you from making the QSO. After all, most other operators (the sane ones anyway) are also at reduced power. CW, because it can still run full power, is a little more reliable, but the difference is often offset by the fact there are still fewer on RTTY than the other modes.
And yes, I have worked several ATNOs on RTTY as the first QSO. Once in a while, it is even the only mode for a given country.
If you check around, you'll find RTTY has (currently) about half as much participation as CW or SSB. That said, the overall number of entities available is about the same in the end. Once in a while, there are still places that don't run RTTY, but even then, so what? It is the many that do that gives you the extra chances over not doing it.
Still, when something really big time comes on line, RTTY operating can be a challenge, especially as the splits increase. A lot of software is really set up to deal with a 3 KHz window (SSB, in other words). It can be managed, but it can also be a pain to manage.
For less rare stuff, the pileups usually stay in that 3 KHz window and the DXing is a little different than either CW or SSB, but overall quite recognizable in terms of figuring out where to transmit to win.
Overall, it's worth overcoming the rabbit fences to get on the air with it. And, you can manage your separate RTTY score just like you do with SSB and CW. That has its own charm.
I've been doing RTTY in some form for nearly as long as I've been DXing. Especially for the more modest station, it's a tool that should be in everyone's bag.