I beg to differ. Eisenhower was quite comfortable with sneaky CIA and paramilitary stuff not involving US combined arms forces. A full-scale commitment of US forces, resembling Hungary or Suez.
That is more of what I was referring to, though I don't think that Hungary or the Suez would be apt comparisons for why Eisenhower would not use American forces directly; that was a whole 'nother clusterfuck that was insanely complex, leaving few good decisions and including direct confrontation with the Soviet Union.
Are you one of those people who thinks Castro only survived because Kennedy was a sissy? If Castro only survived because Kennedy was a sissy, he only came to power in the first place because Ike was a sissy or inattentive. A Dominican leftist regime could have taken and held power during an alt-Eisenhower administration for the same reasons if the movement were as savvy and domestically supported as Castro's. All possible if such a Dominican revolution happens before or instead of the Castro's takeover and foreign policy realignment.
Considering the Bay of Pigs and how Kennedy was all over the place in regards to its planning and execution, I do lay a lot of blame upon him for its failure. That does not of course mean that he was the sole reason, the CIA for example was totally inept when it came to maintaining its secrecy, up to an including when scouting the beach the day of the invasion, but Kennedy could have made a number of decisions that would have allowed the main goals to be achieved, and I see Nixon making those decisions or even going beyond them. Of course Nixon could also be blamed, considering he vetoed the idea of informing Kennedy of the operation until sometime after the election.
I can't really lay blame at the feet of Eisenhower however given real tensions with Cuba did not begin until the turn of '60, at which point Eisenhower really couldn't do much unless he wanted to jump the gun, which wasn't his style as you yourself state; he preferred operations that often were behind the scenes, and which required a year or more of planning.
Funny how Eisenhower never pulled the trigger on Bay of Pigs in his two years of coexistence with Castroite Cuba. It's a legitimate matter of debate whether he would have redeemed Bay of Pigs with an invasion, or have redeemed the anti-Arbenz operation of 1954 with an invasion if faced with the stark choice of failure on the "covert" side or open invasion. Eisenhower also didn't keep large conventional forces in place ready to launch invasions.
Much of this I have outlined elsewhere, and I must be honest in that I am not all that familiar with the Guatemalan "Liberation" operation of '54. From what little I can gather (from Wikipedia of course), American forces were not considered for that purpose because there was no actual casus belli for which they could reason the deployment of such a force. On the other hand the Bay of Pigs was planned with the major participation of the United States Air Force, one of the things that Kennedy vacillated on and ultimately nixed. I'll need someone to back me up on this though, as I myself am not totally confident on my memory there.
Likely result if Dominican revolutionaries start a leftist, Soviet-aligned regime is just it being under high-intensity pressure by an early version of Nicaragua's Contra War, launched from Haiti. (why do an amphib invasion after all). Then it just becomes a question of the DR being able to survive this pressure. Maybe they couldn't last more than a few months. Maybe they could hold on for over 10 years like the Sandinistas, maybe for 50+ years like the Cuban regime.
If the regime is blatantly clear about being Soviet-aligned then I can't really see most President's allowing that to stand especially if we see the OTL lineup, as in not considering direct intervention of any kind.
Again, this is entirely dependent on when, and if Cuba still occurs as it did in OTL. If Cuba falls before the Missile Crisis, well, we could see an analogue in the Dominican and Khrushchev remaining in power longer. There are just a lot of factors to consider, but parallelism is ironically going to be very strong when mulling upon this.
--With Haiti on the anticommunist frontline, this just becomes a superb test of the theory if a) Haiti is doomed to be screwed in all 20th century PoDs and b) if foreign aid for Haiti can be a good thing. Because this ATL would see both higher levels of US aid for Haiti and more commitment of US ingenuity and skill to keep it from succumbing to revolutionary contagion from the DR.
The problem here is Duvalier; the United States is going to be friendly to the Haitian nation, but they may do it without Duvalier being the one at the helm if it was even possible at this point to knock him from his pedestal. What bit I read on "Papa Doc" was about seven years ago.
Well, I would say that a country more distant from the US and with a greater landmass (like Bolivia, or Colombia or Venezuela) could be a better and "safer" place for such an experiment.
Bolivia seems the best bet of that lot.